What are some DIY simple tools to use to make a model scale home?
Thin foam core or cardboard, card stock, and balsa or lime sticks.

All three of these things together are light weight, inexpensive, and should be available at craft stores or on the web (the balsa can be purchased on Amazon but you may find it in JoAnn's). They can all be cut simply with a sharp Xacto-type blade or scalpel. You'll likely be able to find these items at either a craft store or (possibly) an office store. I used to work at a university book store and they actually sold kits for the architecture students in the art section, so if there's a university nearby with an architecture program, see what they have on hand.

A basic guide supports these:


  As far as materials are concerned, unless you have easy access to a workshop and a reasonable level of experience with machinery, it would be best to work with card or foam-board or similar, easy-to-cut materials such as Balsa or Lime wood. In other words, anything that you can cut with either a sharp blade or junior hack saw and stick together with conventional shop bought glues.


It also recommends using some other tools to help ensure your lines are perpendicular (or at the proper angle you wish) and straight.


  And when you are cutting, if possible, try to use a square, especially if you are cutting out floor plates or elevations. Keeping everything square is crucial if you want to achieve a neat, crisp finish for your building. It’s also worth investing in a metal ruler as you will find a plastic or wooden ruler will get damaged very quickly.


As for how to use the knife, the importance is patience and technique. Use several shallow passes to get through the thicker foam or cardboards:


  Whether you’re cutting with a craft knife or a scalpel, it's better to use several light passes rather than trying to cut all the way through with one go. You’ll get a cleaner cut and you’re less likely to slip and cut your finger.


My dad was an architect and these were the sorts of tools he used, so if they're good enough for pros, they should be good for you, too! Best of luck finding the supplies and building your dream home (scale model)! Oh, be sure to do a lot of practicing before trying to build your final house. This is a slow, careful process that takes a lot of practice, so be patient with yourself.