I was looking at buying a Sierra Designs Origami and noticed that it was made from five equilateral triangles. Stopped by Seattle fabrics while I was on the west side and bought five yards of 1.1 oz silnylon (I should have bought 6).

The silnylon was 64"wide. If you make that the height of each triangle, the base (each side) would be 2 * h / sqrt(3) = 73”. You can make the triangles smaller if you want without any additional cuts as long as you align everything to one side of the fabric. I made the following cuts to get symmetric, but not equilateral triangles (I assumed a 60” width).

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With five cuts, I got four of the five sides and two more half triangles that made the fifth. I pinned all the sides together and my wife made the felled seams. Total of about three hours. I just have to add tie down loops.

How I should have done it for five perfect equilateral triangles

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You could have with smaller base and height and two half triangles of scrap and any scrap from the one side.

I rushed the cuts and the build but I have something that I may actually like for $70 in material. This was an experiment to cut my teeth on making our own gear. We made some mistakes but the results are good for how fast we did it. I am a perfectionist if I give myself time. I ended up with taller triangles which I am not sure I like because I didn’t add a zipper for entry (yet). Kind of a junk yard war project with no planning. Worst case, I cut an entry and hem it and use it for extra cover when car camping.

I think that with some care, actually measuring and planning, and more practice with seams, the next tarp attempt will be pretty rad.