Here is my solution to holding the funnel and filter to allow drain back into the tank on our Form3.
It just clips onto the tank and then I can fill up the funnel with filter paper in it and let it drain into the tank while the tank is in the Form3 with the cover down. I leave it overnight.
For filtering we designed a funnel for a quite standard bottle, for me it would be great to have a piece to support the tant and drained it into the funnel, and a modification os this support for a bottle.
It is posible to have the 3D to modiffy it?
Our funnel: Screw-in Funnel by Vikyngo - Thingiverse