Uh, polycarbonate (see PM)... not polypropylene. Big difference! btw, billa, I admire the block testing procedure you developed and display over at overclockers.com!
Also, while 6061 is very easily machined, it has bad electrochemical properties... for waterblock design, I would look to other aluminum alloys (or just copper
) Check the metal stock section over at
www.mcmaster.com ... they always have nice descriptions of the different applications and characteristics of thE materials they sell!