Buchner funnels are common labware used for filtration, typically vacuum assisted, but in a pinch will do the trick with simple gravity, albeit at a much slower rate. This SCAD script is parametric, basing all dimensions on the diameter of the filter paper selected (filter media comes in a variety of diameters). Note that the perforated plate in this design is printed without perforations – they must be drilled. Since prints are typically porous, a sealing step is recommended before use.

Depending on the diameter, a large bridge may be required.

The perforated plate should be at 100% infill, so set solid layers appropriately.

-Enter the diameter of the filter paper, wall and perforated plate thicknesses in the SCAD file, render and save the stl.
-Slice to your liking and check gcode.
-Print.
-Cleanup the print.
-Do a sealing treatment (ABS - acetone wipe should do the trick, but do it outside or under a hood - acetone likes your liver more than you do; PLA - I'm going to try a silicone wipe, will let you know how it works).
-Drill perforations in the plate to your liking.
-Put the funnel on an appropriate container (vacuum flask, Erlenmeyer flask, mayonnaise jar).
-Place appropriate filter media on the plate and wet with proper solution.
-Pour in the slurry and watch relatively particulate-free solution drip out the bottom of the funnel.