My son loves to run his motorized Brio toy train through a cardboard tube, so I created an adapter that allows hin to directly integrate the tube into his tracks. The tube is simply placed between two adapters without a mechanism to secure it in place, but still the exact measures make it quite reliable. If you want to fixate the tube, you might consider adding pins to the design at the outmost parts and punch matching holes into the tube.
This adapter is specifically designed for a tube with an inner diameter of 60mm and a wall thickness of 2mm. I had trouble to find a generic solution for different diamters. If you have a larger tube (smaller ones probably won't fit the trains anyways) you can try to modify the Blender file accordingly. You will find several hidden objects that define the cut-away for the tracks, the connection pin and three tubes that are used with Boolean operators to define the cut-out to hold the tube.
I have printed it in PLA with 0.2mm layers and 25% infill. No supports required.
| brio2tube-female.blend | 909.1KB | |
| brio2tube-female.stl | 53.1KB | |
| brio2tube-male.blend | 909.1KB | |
| brio2tube-male.stl | 55.3KB |
