Are you gonna blow it up or launch it.........or both? I've got some plate steel. I don't think my roller can handle rolling some strips. I've made simple launch platforms outta 4 pieces of steel. Two squares and two strips rolled to make circles, with top one slightly longer to slip over the other and the strip on the bottom taller to be able to drill the hole for fuse or wires in the side of the bottom piece. .Roll the strips and weld the ends together and then weld to the plate, inside and out.
It lasted for quite a few launches until the plates just bowed too much. I used the opportunity to train some NDT and show how to Magnaflux and die penetrate welds.