You can buy sisal twine at Walmart, home depot, Lowe's etc. The twine is a perfect size for lovebirds, budgies, cockatiels etc. Just make sure that the sisal does not have a strong chemical odor or a greasy feel as some places do treat their rope.

For other toy making parts try your local dollar store, dollar tree, etc for other interesting plastic and wood shapes. If you need some other ideas of toys or else toy parts let me know and I will try and direct you to the right place