Ok, here we go.
http://www.users.bigpond.net.au/pippin88/GPU002.jpg
http://www.users.bigpond.net.au/pippin88/GPU003.jpg
The lips around the edge are to be used for mounting.
The bottom one will have four holes drilled in it for the corressponding holes in my GF4. The top lip where above where the boltheads will go will be milled away.
The top lip will have two holes in each sides of the block (8 Total) for bolts that will be glued in to make studs. Bolts used will be 8ba8 (I think) which is about 1.8mm (not sure). The lid of the block will be held on by nuts (onto the stud bolts)
All clear?
Also there is a smaller channel in the bottom of the large channel (Camera screen is broken so I cant get to macro mode

)
The design came from the fact that I couldn't get the small collet for the small endmills to bite and hold properly, meaning I couldn't cut small channels, so I decided for an open flow block.