As I said in the topic "Magnetic Hoop Final Answer"; this is the hoop that my husband and I concocted.
I'll first preface by saying that my husband is a fine woodworker so my hoop is nicely made and many people won't have the same skills to make one like mine!
The frame is made of 3/8" thick X 1/2" wide wood and we sized it to (hopefully) fit all sorts of thicknesses of quilt sandwiches. It's worked fine for all the things I have embroidered so far.
The magnets are Neodymium Rare Earth magnets we ordered from a company, Total Element. Size is 1/2" X 1/8", 8# per magnet.
The magnets are inset into pieces of recycled baseboard molding. The little lip on the molding helps to keep the magnets nicely on the Frame.
With a frame like this you cannot use the Hard plasic grid so it's very important to mark the frame with the design area, especially because the design area isn't centered in the hoop.