KOKUA LIKAaBIKE Rear Light Holder

My son loves his KOKUA LIKAaBIKE and wanted to ride it also in winter. So I bought a LED head light and rear light. The head light could be easy applied to the handlebar. But I could not find a place where to place the rear light.
So I decided to design a rear light holder for this bike and make it attachable to the seat of the bike. Now my son can also ride this bicycle in the dark and is well seen. :)

Printed with support as you can see on the picture. 0.3mm layer hight, 30% infill.