I was not satisfied with the other 3d printed upper rail options for the P90 so I designed my own.
The upper is inspired by the XF50 tri-rail billet upper receiver available for the real steel p90.
The mock suppressor in the photos is the 1/2”-20 UNF thread variant of the 22 silencer that
ANVILAERO has created on Cults that has been modified to remove the baffling and replace it with foam.

The design features standard Picatinny rails and the option of side rails. 
The side rails mount via 2 M5x12 screws the screw into the main body.
The inner barrel shroud uses a ½"-20 UNF thread.

I printed the model using PLA+ on a 0.2mm layer height with a 40% infill however you can print it at what ever prints best on your printer.

The upper was designed based on the dimensions of the King Arms m3 p90 so it may need some fitment to fit in other models. This is the first version of the design and I have not yet been able to field it, so YMMV. I plan to update the model with tweaks once it's been battle-tested.

***UPDATE***

I have since fielded the model and came across the issue of the p90 failing to feed. This was due to the upper not slotting back enough for the hopup chamber to fully seat with the gearbox body. 

The new updated v2 model fixes the feeding issues and currently works!

Any further improvements will be noted as they are made.