Remix of https://www.thingiverse.com/thing:2843552
Discription copied from it:
Katz-Moses style dovetail guide. The magnets keep the blade correctly aligned while you saw your dovetails.

WARNING: You need to glue 8 cylindic neodymium magnets to make this jig work!

How to cut dovetails with this kind of jig.
How to use it with a chisel.