Light Proof 3D printed radiation shield - which material is the best?

[estario]

Hello,
We are trying to make 3D printed weather stations. One of the obstacles we face is finding a lightweight, durable 3d printing material, that is impenetrable to light. Inside the radiation shield is the temperature sensor and we have to shield it from solar radiation to get proper readings.
We tried with ABS and HDPE, but even black plastic at 3 mm thickness permeates light. We are using a TEVO Tarantula 3D Printer.
The solution we found, is to paint the plastic parts, but the results are not satisfactory and it is very time consuming.
We have examined professional weather stations and the plastic parts are very durable, thin and 100% light proof.
This is the pro Radiation shield.
31301730_10214067981725160_2057840967498596352_n.jpg
And this is one of ours:
31284638_10214067981445153_6588574153840787456_n.jpg
Do you have any suggestions? How can we achieve better results?