Chipper; I'm sure you meant to say 3/8". That aside, the only caveat here is to be sure those wheel spacers are all as close as possible in length. Another suggestion might be to get a length of 3/8 I.D. pipe and bring it to a machine shop and have them make the cuts. Cutting these on a lathe would not only insure the dimensional accuracy, but give you a much finer (and flatter) finished surface, where these things sit against the wheel and sprocket.
I've had some pipe cut like this in the past. It's amazing how nicely finished the ends come out. Dead square, as well as a nice little bit of "rounding" on the outer edges. I wouldn't be reticent when it comes to spending a few bucks on these. Keep in mind; you'll only do it once. My 2, I guess.