Nice looking saucer you have there. It's good that you made the motor tube short, because you want the CG to be as far forward as possible. I made the motor tube a bit too long on my 54 mm saucer and that limits the number of motors I can use. I'm wondering what kind of foam did you use?
I made mine from 1/2" insulation foam from the local hardware store. It is a very soft foam. The thin plastic sheet on it was peeled off and then 2 oz fiberglass was used to strengthen it. It flies awesome on motors like the J135 and K185. I've got a build thread going on a 38 mm version in the scratch section of this forum. It is being constructed almost exactly the same way as the 54 mm. I look forward to flying it on an I49 or I59. Here's a couple photos of the 54 mm, which weighs 1.25 pounds.