I just called McMaster Carr and ordered a 6x6" 1/8" thick brushed aluminum plate, for $12 plus shipping. I am going to cut that down, making a precise fitting head for my three Plaubel Makiflexes. The Makiflex bottom plate is 4"x 5 1/4".
I'll machine the aluminum plate to fit the Tiltall attachment. This will be sweet to use. It makes the tripod mounted Makiflex quite portable.
Makiflex Standard 125mm F3.2 GX680 Tiltall Tripod
, on Flickr