A while back, I made my wife some Gridfinity stuff to organize her desk. She wanted a dispenser for the pop-up style post-it notes that she loves, and I made something else (that I never published) that never worked quite right. I saw someone made a holder that printed as a single piece, loading from the side, but not for Gridfinity. But it was enough for inspiration!

This model prints in 2 parts, the bottom prints in the expected way, but the holder itself prints on its side, so as to avoid the need for supports. Pop the dispenser into the bottom and go. It's a really tight fit, so you might need to push it a tiny bit. I also put some glue in there for good measure.

The pics shown here are the model printed in Overture's Purple Matte PLA.