Peter, check the size. The Cuben Solo is made of one piece of fabric 56" wide.
The Solo SpinTex is wider. 84" wide in the front 60" wide in the rear. The Cuben is 56" in the front, 48" in the rear. More material is used to make the SpinTex.
Note that the larger Cuben Tarp uses more material. It needs a seam in the middle to get the width.
In other words, cuben comes in 56" width and the Spin probably 60", to get a tarp wider more yardage is needed. Material is sold by the yard, so to get a cuben tarp wider than 56" or a SpinTex wider than 60", one would need double the yardage. With the SpinTex, 3 yards gets you a nine foot long tarp 60" wide, but to make the tarp 120" wide ( or 84") you need 6 yards. Cut the 6 yards at the three yard mark, ie. in half, join the two pieces along their length and you get a rectangle 9x10. Take a yard off the side (18" off each side) to make it 9 x 7, but you needed to buy the extra long original piece (6 yds.) to make it work.
To make that small cuben tarp on my own I would need 4 yds. The extra yardage would be to cut out reinforcement sections for the tie-outs. Then I would need glue to fasten them, webbing, and gromets. Cuben retails for $30/yd., so there is $120 just in cuben before shipping charges. Suddenly I am only saving $29 at most from buying one better made at MLD!