Cup Holder for Mahindra 2538 Tractor

I recently bought a new Mahindra 2538 tractor. It did not come with a cup holder, so I decided to design one. It consists of two parts, a mount that bolts to two existing holes in the right fender, and the cup holder, which mounts on the adapter.

The adapter is designed to use 5/16 bolts. I had to modify the cup holder to provide clearance for one of the bolts (I routed out a hole in the bottom of the cup holder). If you use a 5/16 machine screw instead of a hex bolt, you might be able to avo