Here is a Cat curve tarp that I made yesterday using a .6oz sil polyester cloth from Dimension.
I was a little disappointed with the trail weight of 380g, I was hoping to be in around the 300g mark. I think that my weights went up because I stuck it together like a sail using Kikusui tape, but I don't have to seem seal so...
It has similar dimensions to the Spinn Twinn but a bit longer along the ridge and wider at the back.
I started by laying the cloth out on the floor doubled up on itself. I them measured out the corners and using a batten to draw all the curves in the panels.
After drawing the shape I then floor cut it.
Using pins to hold both panels in place while I cut away the edges, saving scrap for corner reo's.
I then stuck on my corner reo's and did a double fold over on the edges using 9mm kikusui.
I the joined the two panels together using a felled seem for the ridge line. Then adding the peak reo's after they were joined.
After the tarp was in one piece I finished the corners off with line locks, webs and spectra cord.