This is a bicycle mount for a computer and a display unit of an ebike. It has 22mm and 32mm tubes to which computers can be mounted. The mount goes into the bar end of a steering wheel. This is paraticulary useful for recumbent bikes. The mount is designed for M5 nuts and bolts, but depending on the accuracy of your 3D printer you might need to use M4 bolts. You can download the 3D files over at GrabCAD.
Here is a technical drawing of the design:Bicycle Computer Mount Bar Ends Drawing v2