I highly recommend fluid beds.
I make my own cups using knock out test caps.
Put the test cap in your precut pvc or abs. Use a hammer to knock out the center and discard.
Remove the remaining ring and save. Place your filter membrane over the end and replace the ring.
You should now have a filter cup with a nice tight membrane.
Drill a hole near the bottom in a flat cap, 2" or 3" depending on your desired size,and hot glue in an aquarium valve. Or alternatively you can stick a short piece of tubing in the hole. Then add your valve and tubing to the pump.
If you make them 3" then you can just use a 3"-2" adapter and have both sizes in one fluid bed.
I also use a Knockout test cap to cover my cups and store the paint in the cups
Been working good for me for many years and only takes 10 minutes or less to build each one.
I would rather not have to wipe out a cup every time I switch colors.
I'm also not fond of the threaded fittings.
This is just a much simpler way that works for me.
I have several fluid beds made this way some have 2"x12" tall cups in them and some just have shorter 3" cups.
All are powered by cheap Walmart aquarium pumps. A 30-60 pump will run 2 fluid beds at once.
