Here, as promised is all the information about making your own pin loom.
This site has all the instructions for making several sizes of loom and the jig for working out where to nail the pins. I actually reduced the size even smaller for mine, and as long as you keep the pin arrangment the same as the diagram on all 4 corners of the loom, it works.
I also find that it's OK to just nail into a a block of wood to make a small loom. You can simply take a piece of wood and nails! I used a piece of old cork flooring and drilled a hole in the centre - the hole also not really needed.
The website above also has instructions on how to weave on your loom and ideas on what to make with the cloth.