This is a set of clams to support the Minitronics controller board produced by RepRapWorld, together with its accompanying fan.
The authors of the board have also designed a thingy to attach the fan to the board http://www.thingiverse.com/thing:85977, but well, it was not what I was looking for.

This design will allow you to independently attach the Minitronics board and the cooling fan to the rods of your RepRap, provided the frame is made of 6 mm rods.

• Print 2 miniclams and 1 fanclam.
• Have at hand 7 bolts M3x12 and 7 M3 nuts.
• Attach the miniclams to the 2 holes at the end of one long edge of the board, using couple of nut&bolt pairs.
  I would recommend the edge with the stepper connectors, but this is up to you.
  Make sure that when tightening the crews you left aside of the plastic piece any soldered terminal.
• Position the clams along the rod in the desired position and gently push the ensemble against the bar, until the clams will fully attach to the rod.
• Secure with a couple of nut&bolt pairs.
• Attach the fan to the bracket of the fanclam using with a couple of nut&bolt pairs.
• Position the clam on the rod, somewhere between the 2 miniclams, and push it to attach to the bar, then secure with a nut&bolt pair.