[EricH]

Start with the holes provided in the Kitbot, and bolt (or rivet) to those. Cut parts of the kit frame away as needed/allowed to provide freer motion.

Of course, the attachment may require some right-angle brackets to hold any superstructure on top, and will almost certainly require extra material for the superstructure.

For example, let's say that I wanted to run a single-joint arm on top of a KB chassis. The arm needs to be on the floor within the frame, but will go outside the frame when in operation. I have a plywood bellypan (it's cheap and strong, if a bit heavy). Phase 1, get the vertical supports bolted to the inner frame rails in the right place. If that's impractical due to spacing, make a bracket to attach to the plywood. Phase 2, locate a sawzall or jigsaw or hacksaw and cut out a notch in the front of the frame and the plywood until the arm goes to the floor.

Different manipulators will take different attachment points, so plan ahead. A little bit of pre-planning to use existing holes can help save time and energy.