I have actually been considering making some out of PVC, i have friends that need two, i would like one more
i have a 2 lill fishies for carbon right now and am loving it, basic design, large tube, with small tube directing input water to base so that it is forced to flow up thru the carbon.
I may try to make a few to keep the individual costs low, probably 15-20 or so in parts, hard part is the end caps and bulkheads are the expensive stuff when you can usually find 2 lill fishies for 20-40 buck used witha powerhead and no labor(thanks shortkid09 for the one i have). I am going to hit up home depot today and see if its worth it with parts or just easier to order one online.
if i end up making em ill pm ya.