First I built the frame out of PVC, then I measured and cut the bottom felt. It is 16"x31" so I have room for a 1/2" seam all the way around.
Next I measured out the felt for the sides. This piece is 13"x92". I folded and pinned 10 1/2 inches up, making the top loop for the PVC, then pinned it around the frame to mark my circles for the joints and the corners.
Next I cut out the circles for the joints and sewed the top seam. Then, using the marks drawn for the corners, I sewed the two pieces together all around the bottom piece.
Everything was put together and fit in the cabinet. The fit is good, but I was covering about 1/2 of each intake.
Well, nothing a little sawing can’t fix! I enlarges the holes as much as I could, and I’m pretty comfortable with it now.
Finally I mixed up the soil and filled up the bed. I watered in some of the Soil Balance according to the labels directions.
So the soil bed itself was only about $20 to make and I have enough fabric to make several more. The soil cost me about $185 for two cubic feet, and I have a bunch of peat and amendments left. While I was mixing up soil anyway, I also amended another two cubic feet of my recycled soil with the same recipe.