i use pvc pipe ---i drill holes in it down 2 sides, then hone it gently!! and make all edges smooth!! --i cut 1oz doing this (i compared my home made spacer to the stock profile spacer!! sounds stupid but i've made a couple for freinds now!
its cheap ---and i now have a carbon fider on my bike -i found a lingth of carbon tube --only .30 gram differance between the carbon and pvc!! but it just looks cooler when you pull it apart!!