Make one yourself ... you could carve a piece of wood so that you have a hole for the diode body and a couple channels for the leads, make the channels bend as the leads would normally bend, at the right spacing. repeat this 10+ times and now all you have to do is put the diodes in the form and press down with something to bend the leds into the shape carved in the wood.
You could get clever and make this out of printed circuit boards ... make a pcb with cutouts for the diode body and for the leads then stack a bunch of these pcbs to get the right height. Then you can go from above with something that locks the diode body in place and pressed down on the leads through the stack of pcbs.
Could be made easier if you precut the leads .. again, you could get a block of aluminum to someone with a cnc and have that person cut int the aluminum room for body of diode and channels for the leads to the length you want and once you spread the diodes on the aluminum bar and have them in place, you can just go and cut the extra wire with whatever you have.