We have replaced our old aluminum jib cars, which had developed cracks around the pivot, with a simple dyneema loop around a frictionless sailing ring. We liked the simplicity of that system more than the traditional blocks.
We followed this tutorial on how to braid the loop of dyneema. We made a fid(a hollow spike for use in ropework) from an old knitting needle. We have secured the loop around the sailing ring and on itself, with a few stiches of waxed thread.