E.g. What I used before I had my own printer: https://i.materialise.com/en. Source: about 1 year ago

Https://i.materialise.com/en is the service I've used. Upload the stl I make in blender, and it quotes the price. Source: about 1 year ago

Not for the US, no. But a quick search should give you good enough sites e.g. https://i.materialise.com/en. Source: almost 2 years ago

i.materialise.com , I believe the formats used are .OBJ and .WRL. Source: almost 2 years ago

I can recommend these guys for printing any material i.materialise. Source: over 2 years ago

Hey, I'm in a similar boat (and also freshly post-top). I've had great luck with Gender Free World, but I also got a bunch of shirts made through Ratio. They're not GNC/trans-specific, but they were very willing to work with me on measurements and such. Once my measurements were in there, I just ordered what I wanted. They're not cheap, but I've had their shirts for five years or more, and they've held up really... Source: over 1 year ago

Lastly, I've found just getting custom made clothing is usually best for me nowadays. Woodies has done me right, I have multiple dressier shirts from them that fit perfect, also a denim jacket that is also fit to my size. There is a lot to be said about getting custom made stuff for us larger folks. For the price they charge, and how long they have lasted, I would suggest that. I know there are also... Source: almost 2 years ago