repost / remix of the original, which was relatively small 
the version I've printed is 20cm at its widest, I've also made a 30cm version 
These are more suitable for actually ceiling mounting on a pendant light in a decent size room 
when the light shines through it you can see the thicker corners quite clearly which gives a nice effect. 
the hole to mount the light pendant is 29mm, standard in the UK. 
in the EU its 40mm I'm not sure about elsewhere but easy to modify for yourself. 

print settings 
Printed in ESUN PLA+ 
vase mode extrusion width 0.6 mm 0.1mm layers 
minimum bottom layers needs to be about 2mm worth to give it a solid base. 
edit- in retrospect i should have printed thinner or used a more translucent filament. 
as my print reduced light output a little more than a lampshade should. 

i printed with on masking tape smeared with superglue 70deg first layer 
20 deg after that, this print took 21 hours so for these long prints i mount like this 
as its very reliable but also uses up less electricity bed heating over all those hours

having printed this as above i found it a bit thick, i would recommend a more translucent filament to let light through better and maybe a thinner extrusion