Attachments

A simple 1 cm grid of 3.2mm (1/8") holes makes a great non-proprietary surface for
mounting small parts. Even boards that weren't designed to fit are close enough.

Some adapters are mounted through disks. This type can be quite strong,
with larger slots and hole patterns for more rigidity at the cost of more space.

And other things are just bolted on top of disks. Cameras and sensors need
to be securely mounted, but strength and rigidity aren't as important.

Something big, like a manipulator arm, would need a large footprint
for leverage and careful placement of weight, eg. battery, for counter balance.