Ok guys i've got an update... i've started making some single prototypes and will get onto the final design of single and double mounts in the next few days.

Specs on the first prototype single mounts i've made are:
- weight 7 grams
- size 12mm high * 30mm wide * 24mm long
- mounting....
can be attached from the side like in NST (i just used two screws thru a bulkhead into the plastic) but could easily be bolted.
alternatively could be attached from above or below the mount. I'll put a picture up soon to make things clearer.

Hope this sounds like it will suit most robot's requirements.