I tried making one with a spare chain saw chain, It did not work:

1. All the teeth bite into the wood and the pulling load is too much for anyone to pull.

2. It would only cut in one direction.

I think this is why the UST only has one tooth in five and they also act in opposite directions alternately. If I owned a tool to break and make the chain it could have been adapted.

Far cheaper to buy the UST which works brilliantly.