I used fiber glass mat and epoxy to make a clean surface. I don't know how the glue will hold up. So over engineer it !
I sanded it :
I painted it in black with paint laying around :
My drill is working great, has a bit more torque as far as I remember, and use the same battery as the other tools. It's really great !
If I had designed the 3D from scratch I could have used just one 3D printed piece, but less work is better.
Quid of the project 4€ for the glue, the rest was laying around in the workshop.