[Jared Russell]

We usually build our chassis with Bosch-Rexroth aluminum extrusion (20mm profile in recent years), so we outfit our bumpers to take advantage of the T slots in the extrusion.

The bumpers have bolts put into them (head side out). We usually mill out the sides of the channel at the top of vertical members (in the corners of the chassis) so that there's a place to insert and remove the bolt heads. All you have to do to add or remove a bumper is to put the bolt heads through the hole and slide them down into place.