Henlo everybody! Here's my entry for the TARDIS of the Week (Rainbow theme). For this idea, I went for a TARDIS in the Classic series's style (Colours; roundels; non-Police box interior door), but with a type of architecture you could find in the New Who series (Platform; lower level; more space; etc.).
I tried not to put colours everywhere so it wouldn't be to "agressive" to look at. For that effect, I placed some coloured glass in the ground, the walls and the roof (I used glass instead of concrete because the coulours are transparant so it matches more the rest of the TARDIS) while white still remaining the majority colour not to lose the Classic style I wanted.
The lower level is the most colourful place of the room with a spiral of coloured concrete, glass and terracotta on the ground for a fantasy effect. I also placed glass panes on the walls with different roundels behind them because why not. It's also supposed to be the "habitable" part of the room with Library blocs, a hat stand and a comfy chair.