Don't lose any pieces https://collection.sciencemuseumgroup.org.uk/objects/co62748/babbages-difference-engine-no-2-2002

No computers = no transistors? No electrical logic? So, basically you're looking for a mechanical computer?

My clanker said its possible but with thousands of moving parts.

I trust a Nintendo 64 enough for this, but if someone managed to make a compact mechanical SHA calculator, I have to admit it would be awesome to behold.

Is disassembly a requirement because you want to be able to move it, change it, inspect the whole thing, or something else?