Here is an 8mm Rod Block Pillow Mount for use in fastening guide rods for use in CNC applications. It is specifically tailored for use with 80/20 aluminum extruded framing, but can be mounted onto anything.
The part mounting holes can accept 6mm bolt hardware, and there is a single 3mm x 22mm screw (with nut pocket) that is used to tighten the user's 8mm rod in place. The mount's overall size is about 53mm L x 20mm W x 34mm H and the 8mm rod (center) is spaced 21mm above the mount's base.
Printing with your favorite SkeinForge settings will work fine with this object. I have printed this object rafted on the stock MB platform and raftless on the HBP without issues. Setting INFILL DENSITY in SF's FILL menu to 0.25 printed the mount plenty strong to support a 400mm rod very solidly with a rod mount on each end.
The mount requires very little post-printing work. I used an X-Acto knife to clean out the part's 6mm base mounting holes and the slotted 8mm rod hole. The 3mm rod griping hole and 3mm nut pocket, I just worked the screw and nut into place without much else. You might find that running a 3mm drill bit through the hole will make the assembly process a little easier.