Quick-attach blocks for prototyping

These are quick-attachment blocks using 10-32 or 10-24 socket head cap screws for prototyping purposes. Attach block A to one object with two countersunk screws, attach block B to another. You can now slide the blocks together and pin them in place with a final screw.

This gives you a fully-interchangeable (but admittedly somewhat clunky) attachment point for actuators or whatever you want, so different subteams can swap their mechanisms in and out from a common mount point.