Here is thr mini cyclone I just built from scrap lying around for the top of my Ridgid shop vac. It's built the same way as the cyclone I just made so I didn't feel he need to repost them again.
I'm using the motor mount plate to rout a groove for the filter to sit in. The piece on the bottom is what the filter will mount to.
This is the router bit I used for it.
And here is the finished piece the filter mounts to.
Here are some pictures of the assembled top for the shop vac. I still need to attach the pvc pipe from the top of the cyclone to the filter box, rout a groove for some weather strip to seal the top to the bottom of the vac and make a transition on the input to connect the hose to.