Enjoy making it! My teens make them now and they’re very mathematically / engineering precise.
Top tips -
The biscuits swell and change shape a bit when cooked. You can easily trim them back to shape when they’re warm out of the oven, and if you forget or need to adjust later, a microplane grater is good at filing it down a bit.
If you’re doing the “crushed sweets to make stained glass windows” thing, don’t forget to add the sweets in before it’s all finished baking!
If you’re making icing to stick the pieces together with, you need far less liquid than you think to add to the icing sugar. A really tiny amount.
Buy extra icing sugar in case you make the icing too wet and can’t stick the pieces together.
Flaked almonds look really pretty as roof tiles.
Leave a gap so you can put a small bundle of led wire fairy lights in there to glow through the windows. The battery pack can come out the back. It looks really pretty!
Oh, and it lasts for quite a while. A good week or so easily.