Restoration can be full of creativity sometimes. Here, they have used a special 'rack' of sorts that mounts to where the Fića's suspension does, and the car can be moved around using the rack's casters. This is also handy during the painting process: no wheels to cover up!
Another rack attaches to mounting points near the casters, allowing the car to be flipped on its side, visible in the photos. While the car rests on this side portion, work on the bottom of the shell can be done more easily.
Click any photo to enlarge it (both are high-resolution).