So I've got a number of projects going that require acid etching. I've been practicing and feel pretty good about everything but protecting the threads on my TCSS parts. I've tried shipping tape & nail polish. I haven't been able to find plastic end caps or better yet a plastic MDS piece that would screw into my aluminum piece to seal the threads from the inside.

Any suggestions or hints would be most welcome.

Thanks so much & MTFBWY