I painted the inside of the box with an ordinary paint and put in beams to make it look like a half-timber frame structure. I learned from Nisbett's book how to make wooden strips look old and uneven. I put in a floor made of dark wooden strips. Then it was just filling the room to the brim with this and that. The shop changes all the time because, as in a real antique shop, things come and go. Lots of things have moved into new houses and room boxes.
This is a picture from an early stage, before I started the Tudor house and the modern house, and before other room boxes. Most of the things here are leftovers from the Victorian house, although I did make some things specially, for instance the jewellery display cabinet in the front, with teeny tiny rings and necklaces. In the picture below, lots of things have moved elsewhere and lots of new things were added, but I also made paintings, clocks, lamps (thimbles and chess pieces) and other things that I use when I need them. I don't bother about scale. Everything I buy at flea markets and thrift shops goes in here, unless they immediately find a place elsewhere. There is so much I don't need to make anything for this room box. There isn't much challenge, but on the other hand it's fun to rummage through the shop to find something useful, just like in a real shop.