Could you use replicators and transporters to build ships or shuttles?

[Kamen Rider Blade]

Except that it was established in TNG it can do just that.
Its hardly world breaking or too powerful, and there can still be some limits.

According to the TNG episode "Rascals".

It was a random "Spatial Anomaly" known as a "Molecular Reversion Field"

According to Memory Alpha, the Transporter interacted with tis MRF Spatial Anomaly:
The molecular reversion field obscured portions of their patterns, in particular the rybo-viroxic-nucleic structure of their DNA, and the transporter re-materialized all four without it.

As for how they solved the de-aging issue:
In 2369 after an unusual transporter accident due to interference from a molecular reversion field, several of the key viroxic sequences of a few USS Enterprise-D crewmembers, including Captain Jean-Luc Picard, Keiko O'Brien, Ensign Ro Laren, and Guinan, were found to be missing. As a result, they emerged from the transporter as younger versions of themselves though all their memories and mental capacities remained those of adults. The accident also reduced a specimen of Draebidium calimus to seedlings. Accelerating the growth of the plants proved effective in returning them to a mature state, though this would not work on humanoids. Eventually, they were helped by artificial re-insertion of the RVN sequences.

NOTE:
RVN has not been identified in real life. At the genetic level, physical development is believed to be rooted in tailoring gene expression according to cell type, subcellular location and time. These processes are in turn coordinated through cellular signaling.

Chock it up random Spatial Anomaly for causing this.

But I definitely wouldn't want to be a guinea pig for reversing the age on the body.

There seems to be no known way to control how far back you age.

The RVN also was a feature of plants like Draebidium calimus
The accident also reduced a specimen of Draebidium calimus to seedlings.

I wouldn't want to have some random person test age reversing and turn me into a baby or a fetus.

And the fact that RVN isn't a IRL concept, I'd rather Star Trek avoid using fake medical terminology if possible.

If you want to go down the "Mad Scientist" route of experimenting on living people to reverse their ages for "Immortality".

Be my guest, but I wouldn't want to be responsible if you screw up or you reversed a persons age too far and the body couldn't possibly contain the memories of an adult.

It seems to be "Plot Armor" that allowed the children to retain the memories of their adult selves.

I wouldn't want to be the ones trying to research the MRF (Molecular Reversion Field) Spatial Anomaly.

There's alot of danger involved in doing that.

Imagine what could happen if the MRF inverted for whatever reason and caused the subject to age?

And if you accidentally age a person and kill them?

Then what?

There are WAY too many issues with this line of R&D, it feels like it would fit more into an episode of "FRINGE" where some mad scientists learn of what happened to JLP, Ro Laren, Guinan, & Keiko O'Brien and tried to re-create this tech and for all of it to go wrong.

 

[publiusr]

By the 32nd century, the transporters should be able to do this things. A Founder might still slip in, but a person infected with THE THING restored to normal.

 

[Gingerbread Demon]

By the 32nd century, the transporters should be able to do this things. A Founder might still slip in, but a person infected with THE THING restored to normal.

That could be an interesting story. The Thing is a fascinating creation by its writer but what was the Thing's natural state when it wasn't imitating other life forms?

 

[MAGolding]

In John W. Campbell's ""Who Goes There?", publishe dunder the pen name Don A. Stuart, the "thing" was found in a spaceship crashed and buried for millions of years in the Antarctic ice.

http://www.isfdb.org/cgi-bin/title.cgi?860248

The spaceship was built and designed for either members of some species that the "thing" was infiltrating or by the:"things" themselves. Thus the form that the "thing" had when found was either its actual native form or else a disguise used to impersonate a member of another species.

In the story, the characters used a lot of sinister and frightening adjectives, worthy of H. P. Lovecraft, to describe what that form looked like. But readng the story as a child I thought that objectively it might have looked kind of cute.

 

[dupersuper]

That's your head canon, you're entitled to it.

You want the Transporters to be the "Eternal Fountain of Youth" where it can revert your body to a younger state while keeping everybody's memory in tact.

That's WAY too powerful and world breaking.

But it's your head canon.

How is it head canon if we've seen it on screen multiple times?

 

[Kamen Rider Blade]

How is it head canon if we've seen it on screen multiple times?

How many times have we seen it through Trek?

How many times have they been caused by some sort of anomaly?

Are the anomalies reproduceable?

Can you trigger the Transporter of Youth on command?

 

[dupersuper]

How many times have we seen it through Trek?

How many times have they been caused by some sort of anomaly?

Are the anomalies reproduceable?

Can you trigger the Transporter of Youth on command?

April and his wife de-aged in Counter Clock Incident
Picard re-incorporated in Lonely Among Us
Pulaski de-aged in Unnatural Selection
The kids in Rascals are the only ones I recall hinging on an anomaly.

 

[Ray Hardgrit]

Plus there's The Lorelei Signal as well. And they reset their ages in Rascals without the help of the anomaly. Each time they used the pattern stored in the transporter, except for Unnatural Selection which just needed a DNA sample.

 

[Gingerbread Demon]

With the transporter who needs funeral homes?
And with 32nd century improvements who knows?

 

[Kamen Rider Blade]

Picard re-incorporated in Lonely Among Us

In "Lonely Among Us", Picards Physical Body was transported into the cloud as a form of energy.

After searching for over an hour, the Enterprise still cannot find Picard's energy pattern. Riker, seeing no other option, orders La Forge to set course for Parliament. But, Troi senses Picard. He does not belong with the rest of the lifeforms in the cloud and needs help. Riker tells La Forge to move the Enterprise into the cloud, so they can find Picard's energy signal. At first, there is no sign of Picard anywhere in the cloud, but on La Forge's helm console, the circuits re-arrange to form a "P". Data surmises that Picard has found his way into the ship's systems. Data asks Troi and Riker to accompany him to the transporter room.

"P? For 'Picard'?"

Since Picard's physical pattern is stored in the transporter system, Data attempts to recombine his energy pattern, as he hopes that Picard has worked his way into the transporter. Data energizes and Picard materializes on the transporter pad. Picard has a vague memory of what happened to him, much like Worf and Crusher. Riker tells Picard that he should head down to sickbay, as Dr. Crusher believes Picard is very tired

Since the Transporter Phases the Body's base matter into a energy state and back, the Transporter System had the data files for what arrangement his body was supposed to be in.

Ergo, when Picard's energy form was reverted to it's normal state, he didn't get "Younger".

In the Counter-Clock Incident, the crew visited the Anti-Matter Universe. The Universe acted opposite of what our Universe does and caused the "De-Aging".

The Transporter was used to reassemble the crew back to their "Original Age" since the Transporter stores a record of their original bodies arrangement, ergo re-shuffling the body back into it's original form.

In "Unnatural Selection", Pulaski's sudden advanced aging was caused by the genetically enhanced children's Immune System.

Data's analysis is conclusive, and unfortunate. As he explains to the astonished Kingsley and Pulaski, the antibody the children's immune system created to counteract the Thelusian flu does more than attack the virus; it interacts with normal Human DNA to change sequences which affect the aging process. The children are in fact more than carriers; they're the cause. Since DNA is self-replicating, the effects are irreversible, and as evidenced by how rapidly the crew of the Lantree were wiped out, any infected person is capable of infecting others.

Pulaski sadly and silently accepts her fate, while Kingsley tries in vain to get a hold of herself, but breaks down in tears nonetheless: her experiment, of which she was so proud, has at once succeeded beyond her wildest dreams and proved a miserable failure: her children are so "advanced" that they can never be allowed any contact with the rest of humanity, as they have already proven lethal to herself, Pulaski, the science team, and the crew of the Lantree.

The Transporter using Pre-Infected DNA samples to reverse the aging of Dr. Pulaski was a hail mary that worked thanks to plot armor.

However, after Data is screened for organics and beamed aboard, Picard asks him about another idea. Since the genetic changes are the cause, they could take a sample of her genetic code and have the transporter reverse the transposition. Chief O'Brien says it will work, but it would be risky, since they will lose her pattern if it doesn't work.

It takes some doing to get a DNA sample; Pulaski's records have not arrived at the Enterprise from Starfleet Command yet. Riker and Data search her quarters and finally find a hair follicle on her hairbrush. Picard calls Pulaski. The bridge crew and Picard are shocked by the image of severe deterioration, now looking much older than a hundred years.

The captain explains the possible solution to the terminal doctor. Pulaski, now totally exhausted, out of time and options, is willing to give it a try. Troi is very shaken and sad, seeing and possibly feeling Pulaski's terror, despair and unbearable suffering. O'Brien warns Picard that the trip is one-way only; if the procedure doesn't work, Pulaski can't be beamed back to Darwin Station. Picard takes the transporter controls and assumes full responsibility for the attempt so that O'Brien will not be to blame should something go wrong, to O'Brien's gratitude. After a tense several seconds of controlling the transporter during beam-in, the doctor, restored to her proper age, appears. Picard admits to her had the procedure not worked he would have had to beam her pattern into space. Pulaski doesn't mind, since she assumes the worst whenever she uses it anyway.

Since Dr. Pulaski had "Plot Armor" to back her, I'm reminded of all those folks who end up in some sort of Transporter Accident and gets sent to that special facility that's managed by StarFleet in Lower Decks when Boimler suffered a Temporary Transporter Accident and always emitted a weird noise.

As far as "The Lorelai Signal", The Transporter was able to reset the aging effects that the Species of the week caused to the male crew members.

Although feasible, this procedure has never been attempted before. Spock states that the odds are against them, 99.7 to 1. If it fails, their patterns will break up and scatter in space.

Scott, who, despite still having a severe headache he and the other men still all have, is no longer affected by the alien probe. He transports the four aged crewmen to the planet's surface and prepares to transport them back aboard upon reprogramming the transporter. Despite a brief scare, their transport-transformation is successful.

Back in the temple on the planet, Theela destroys the opto-aud, the probe that lured men to their planet, with a phaser, as part of a prearranged agreement. Uhura explains that a crew of women will bring a ship back to transport the alien women to the first suitable planet, where, according to Dr. McCoy, their physiology will return to normal within a few months, ultimately offering them a better future than immortality.

So basically in every instance, the Transporters reset the people's body back to where they were at the start of the episode due to outside factors affecting the body & life moves on as normal.

So the Transporter isn't used as a "Fountain of Youth", but is a "Reset my body from it's crappy damaged or changed state to before it got to that point".

It's basically similar to a "Elixer" from most JRPG's that restore you to full HP, cures all ailments, and restores all your Mana.