here is an idea grease the bucket with axle grease so concrete will gome out after it hardens. place bucket in center of sheet of plywood, screw the bucket from the inside ,to plywood with sheet rock screws. after condo is set up tilt condo on its side to slide it out of greased bucket. then you can start all over. the sheet of plywood and bucket can be used over and over.
even better if you rip the ply wood in half first, lay the two halves out like a cross, screw them togather with sheet rock screws. place bucket just below sross piece so you can remove the screws holding the cross peice after it sets up so you can easily turn it on its side.this is all theory but I think it should work well, and plywood base and bucket can be reused many times, 1/2 " ply wood should be heavy enough.