I took my 42 x 68 in summer quilt that I had made out of primaloft and 1.1 oz ripstop two years ago and cut it down to 42 x 53 inches, sewed up the foot box and put a draw string at the top.
Tonight I'm going to rework it to make the footbox smaller. My orignial idea was that I could still use it as an overquilt, however, it's too narrow for that anyway, so it would be better served as a inner quilt for my ultra 20 should I need it.
I'm also going to sew a strap on it to simulate the Arc AT. The Arc AT should be a solid 20 degree quilt given it's loft, however the Primaloft mockup would only take me to the high 40's, so it's not a perfect mock up, but I'll see how I like the sizing.
We'll see how it works out I'll post results in the MYOG section.