Same engine as the pendant lamp — flipped so its top mounts onto the base.
Match the base's Rounded W/D/R so the cupola seats flush.
Outer Ø of the seating lip. Match the base top hole (currently 33.50 mm).
How far the lip drops into the hole. 6–10 mm gives a solid seat.
Radial slack. 0.30–0.40 mm suits most FDM printers.
Tip: set Skirt Ø ≈ base top hole so the cupula seats snugly.