It is done!

Added some cardstock cutouts to simulate bricks.

Glued on more stirrers for strenght and wood simulated interior.

Brown drybrush interior, grey and white exterior. With some wooden floor tiles and heroquest furniture it does not look half bad!

Brick effect.

Mini for scale.

Visible corrugation on the corners is not pretty, but I have to prioritize the ability to fold it. No roof is intentional because the monsters can climb through the roof in the scenario.

Lessons learned: paint all pieces before assembly. Some warping to be expected. Looking forward to play with it!