A while ago I saw a model barn on e-bay. It was advertised as for use with 54mm soldiers.
I thought , at a pinch, it might do for a planned 40mm project. If not I could go retro and
paint up some 54mm figures for a skirmish. The barn wasn't expensive, I put in a bid &
got it.
When it arrived...

It was more for 25mm!
Not only that, it was cast from rubber which had badly warped.

I left it for quite a while, but then it worked its way towards the work-bench.
Worst of the warping was cut out, the main part stuck to a placemat base.
That took a lot of glue, filler, weights & time.
Then it started getting thin washes when ever there was a bit of paint left from
doing something else.
NOW it is ready for gaming.
