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Greg from the Small Planetarium group asked me about the patterns I used for the cover. Well, they're really very simple! Click on the images on the right to see the sketches I made while laying out the cover. I use the same color coding as used in the 4v assembly diagram at DesertDomes. As mentioned before, the cover is composed of three layers of five segments each, connected end-to-end in a ring.
The bottom layer has the largest segments (16 triangles each). I wanted to use the sewing technique described here, which meant adding a little extra fabric (borders) around the perimeter of the segments. On the bottom layer segments, I had to add wide borders to the left and top, and narrow borders to the bottom and right. The little wedges within the segments are not cut out, but folded up and sewn flat against the cover. If you're planning on using your dome outside, make sure that the opening of the fold is always pointing downwards, to prevent rain pooling in the seam. The result is a piece that cannot be properly folded, since it is already beginning to be curved.
If you want to be able to enter and exit your dome without having to lift the entire thing (highly recommended!), you'll need to design in some kind of a doorway. I did this by making a vertical cut in one of the bottom segments, straight down the middle of the purple/green/green and purple/purple/purple triangles. I put in a zipper and also added a little awning, which you can see in the photo of the finished dome.
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The segments of the middle layer are 12 triangles each. The top of each segment has a wide border, the other edges (left, bottom and right) have narrow borders. Note that I moved the wedge on the left inward (by rotating the red/yellow/yellow triangle against the other red/yellow/yellow triangle. The reason for this is that otherwise, there would be too many layers of fabric coming together at that corner to be sewn properly anymore.
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The segments of the top layer are very simple, only 4 triangles each. Only the top has a wide border, the left, bottom and right have narrow borders. For my tent, I removed the red/yellow/yellow triangles on all five segments and replaced them with a clear plastic pentagonal skylight.
Before you start drawing and cutting fabric, I recommend you make a paper model using these patterns, including the borders, to familiarize yourself with the layout. Then, after the segments are all prepared, start assembling the top segments, then add the middle segments and finally the bottom segments.
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