I'm doing dungeon fabric right now. I'll have a separate folder for the furnishings, but currently I've got all your crates, tables, beds and tapestry needs covered. Unfortunately they were first created for a secret map I can't talk about until after April 9th

I'll get the portcullis and altar done though - they are good ideas. I already have some pillars, I might do another for variation. I also want to add a dais, and some barred walls.

Oh, now here's a question. The 1st edition DMG had a symbol set in it somewhere as a legend for dungeons if I remember rightly. Now sadly I did not manage to bring my 1Ed library over the pond so don't have it handy. If anyone does (Turgenev - I'm looking at you), could you post a list here? That's got to be one of the more definitive breakdowns of dungeon furniture out there.