I find non-looping solutions lacking in aesthetics and generally avoid them like the plague, but today I shall bite the bullet and make one for the sake of saving cost. Two pistons are sufficient to handle all the assembly, but the crux is handling the waste lead. A normal arm behind the output buys 3 extra hexes of waste storage, and there is an additional unused hex next to the glyph of unification. I think the best solutions will find ways to handle the waste without needing a third arm, and one arm solutions are probably not possible.