Petg Safe For Lizard. I also optimized the seal, it's about an 80% seal. Petg is both vaccum and thermo formable and can withstand high pressures without cracking.
Petg is a food safe material. I have a sealed breech pusher and an 18 barrel. Ensure the sealant of choice is food safe, and give your model a good rough sanding before you apply a few coats.