Fit!

Phew.  No matter how much the base board and the factory framework were measured and re-measured before cutting and building into a glued block, it's always a relief when they actually do fit rather well together.

Now to get some paint on the framework - mainly to seal it against moisture as it's going to be clad in 3D-printed brickwork subsequently.

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So far, the entire structure is made from spare / recovered wood from past projects etc. including the acres of thin ply that was formerly the curtain pelmets in the lounge.