If it’s just the frame, you could probably get away with something super minimal. Like a simple wooden dowel with a little radius out of the end for the top tube to sit on.
If its just the frame, a few nails on stem, seatpost and BB will also do the job. I did it too. You can see it in my middle-picture in the upper right corner.
Any details on this? Wouldn't mind one myself. I need to hand two frames (only) on a wall and need something minimal.