Just finished a Magna UQP/Poncho from some spare rip stop I had. I didn't have any sil, so I made my own coating using the instructions from the 'make your own sil' thread. I even made a detachable magna hood that attaches to the magnets on the head hole for when its in UQP mode.
I'll let the sil cure and give it a test. Hopefully its waterproof enough for a poncho. If not it should still work well enough for an UQP.
Now I just need to convert my hammock to use magnets, but that's a project for tomorrow.