Have you looked at Lowe's? They make 3/8" bars in length from 1" to 4' long. You might be able to cut one down to size if you needed. My suggestion would be to get a PVC pipe coupling (about 2") and a 3" 3/8 bar (should be in one of the drawers). Stick the bar through the PVC, put two washers on either end and then secure it with 2 3/8 locking nuts. This is what I did a while back, but it was 6,12 and 24" bars.