There are many ways in which miniatures for doll houses can be made quickly and easily, especially if you have access to the internet.
Several web sites dedicated to the hobby have a few items that can be printed off, cut and glued, to make things. A Google search for “printies” will bring up many examples. Most have copyright protection, so you can only use them for your own projects, but they can give you a lot of inspiration for other types of projects.
You will be able to find a selection of items from wall paper to party banners. Many are available in 12th, 24th & 16th scale, as well as what the Americans call play scale, which is suitable for Barbie sized dolls. You will also be able to find 144th scale houses, which can be used as a 12th scale in your own 12th scale.
All you need is the time to look for them, a sharp pair of scissors or cutting knife, and some good glue. Tacky is appropriate for most of them.
Go and have a look - you may be pleasantly surprised at what is available