Adapter Marble Run Duplo (Đáy Ống/Đỉnh Duplo)

Works with the Marble Genius brand marble run, but it will work with other similar sets as well.  Just make sure the top of one of your tubes is approximately 23.6mm in diameter.

This adapter allows you to stick Duplo blocks on top of marble run pieces.  See https://www.printables.com/model/803573-marble-run-duplo-adapter-duplo-bottomtube-top for the opposite.

This block is very short to make the print time as quick as possible.  I printed with a brim, but no supports.

Note: There is extra headroom designed in above where the tube will insert (there is an angled chamfer there that designates this area.  This helps if your printer has trouble with overhangs and leaves some hanging bits or if you use supports and can't remove them all the way.  Just leave that stuff up there and it shouldn't interfere as long as it doesn't hang below the chamfer.