I needed a trailer. I found a great small motorboat trailer at an estate sale but it needed cross arms for a cat. I found them at my local city public works dept. The 1 1/2" square tubes used for street signs. They are quality galvanize and most are drilled every 1 1/2" that lightens them and gives you attachment points. These things generaly get knocked over by drivers and the remaining portion is plenty long enough.
I found it finished off my trailer, it is sound, doesn't have that "home made look" and is actually a better trailer than the special purpose cat trailers you buy.
NaviGator