Instead of the usual Rival-to-Picatinny adapters/risers etc. I decided to model the whole damned thing.
That's what this is, a 'drop in' replacement for your Zeus rail which converts your blaster from Rival to something a little more universal.
Printed twice so far, first was a full print with minor issues, so I fixed those and reprinted the problem part - this now fits and highlighted one more issue which should be fixed!
Let me know if it's still a problem.
Run a 2mm drill down the holes in the RH side to allow the standard Nerf screws to clamp it all together, and most of all, enjoy.