Most DIY kits come with a paper scale. Use it! Even a slight misalignment in the numbers can ruin the 3D effect.
3D clocks require special mounting:
(e.g., neutrals, metallics, or bright colors) 3d wall clocks
Dual-plane hands — hour hand on a lower gear, minute hand on a raised shaft (creates overlapping shadows). Most DIY kits come with a paper scale