One of the most important things in a studio is done! All self-made 18 wall panels and 4 bass traps have been set up. The panels around the drumset do actually nothing for the drumset itself since it is fully electric, but they are preventing reflections to hit the other side of the room where the mixing desk is at.
The size of the wall panels is 140x68x9cm and they are filled with 8cm Rockwool Termarock 50. This material has a flow resistivity of 16000 Pa.s/m². With an 2cm air gap behind the panel it has an absorption coefficient of ~0.6 at 200Hz which is pretty good.
The bass traps have an edge length of 60cm and cover up the entire corner. They are filled with Rockwool Sonorock with a flow resistivity of 6000 Pa.s/m². The big 20cm air gap in the corner the bass trap has an apsorption coefficient of crazy ~0.6 as 50Hz. So it basically kills reflections of extremely low frequencies.