The BATFE shouldn't have a problem with your design, because it doesn't appear that it can be attached to a firearm. Well of course anything COULD be attached somehow--even an automotive oil filter.
Also given the plain language in the Bill of Rights and Constitution, the ATF shouldn't have a problem either (LOL...yeah right)!
If you want to increase its strength (not necessarily what you'd want, given that a stronger device might be decreed to be a "silencer" by the ATF), then get a printer that
can handle polycarbonate nozzle temperatures, or maybe use a nylon filament formulation. Even a PC/ABS blend would offer an improvement and not be quite as challenging to print as PC and nylon.
ABS suffers from significant inter-layer bond weakness (what I call "grain" weakness). You can mitigate the shortcoming by dipping your parts in MEK (preferred) or acetone (not quite as good). They will come out cosmetically smoothed-over a bit and the layer bond strength will increase too. I was an experimenter and contributor in the early Defense Distributed days (right after Haveblue made his lower and then Cody Wilson set the media ablaze).
3D printing is a fun hobby and proving its capabilities was satisfying, but I prefer to machine lowers and parts and I hold a few ATF "silencer" Form 1 / tax stamps too.