Hi Lozza , I have built two jigs a couple of years ago , its reasnable simple .
We used a Ford rear axle as a turn table ,made a big steelplate with tree arms and used a lathe juck to hold the rim in place , the middle has a spiget to hold the hub and you can centre the hub with the rim, then all you have to do is , feed the spokes in and tighten them up . One wheel takes about 10 - 15 minutes. You even can drill the rims if you have to , to line up with the hub. Easy , anyone can do do a wheel with that.