I think so to. you should get some special Copper milling oil, yes i mean oil cause thats the best for milling copper, better than most waterbased coolants.
This Block is not exactly homemade, cause i run a very very small german watercooling shop and manufacture these blocks in quantities which don't get over ten pieces very often, but it is a Prototype so its definitely near to homemade. The delrin is fulli milled and there are channelsin the base, so flow should be not too restrictive for only 15mm width overall.
It is designed to help cooling the mosfets when there is not airventilation because of passive watercooling.
It is designed for an Gigabyte M59-SLI nforce5 mobo, but a similar but some milimeters shorter variant also fits the newer asus boards.
here shown on an old ECS SocketA mobo just for the pics
