My air cleaner is made from two breathers from some '90s model TBI trucks.
I started by cutting off the snout and the bottom out of one air cleaner to get just the "ring":
I then removed the snout from the other air cleaner and filled the snout holes:
I stacked the ring from the first photo above into the base from the second photo and plug welded them together.
After lots of weld smoothing and some paint, I ended up with something that looks like an old oil bath air cleaner. It pulls air in through the 1/4" gap between the lid and base: