Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

Thanks, Stoker and Dennis, for your suggestions. The silicon should work nicely.

Of course I can drill a hole! I can either tap the material if it's thick enough or drill both parts and add a hollow carrier threaded externally on both ends; just need a pretty slim gauge glass for this. I'll work it out, and can't do worse than ruin what already doesn't work....