One might need to consider the copyright / patent implications though?
If you won't sell it as lantern part, there is no issue.
Otherwise I would guess 3D printed template and a sand cast has the highest chance. You may even start from a 3D scan, oversize it in a CAD, make adoption for the sand casting process and viola.
Directly 3D printing the lantern parts won't work well. 3D printing uses materials that do not handle heat well, plus they tend to corrode pretty fast when exposed to sunlight. The fact the 3D prints are rather porous is quite a factor here (oxygen gets access deep into the material).
