This is just one of the blocks you can do with 16 half square triangles (HST) but the possibilities are endless.
For this tutorial I start with 5 inch squares, which gives you 2 inch HSTs, but you can start with any size square.
You will need to trim the resulting HST to size afterwards.
Here is a 2 minute video showing you how to make 8 HST at once:
Example blocks with 8 HST
Example blocks with 16 HST in 3 colours
There are many more blocks you can do with HSTs. A quick Google search will confirm that.