Any auto jumble has extensive stocks of fasteners. I stock up when we go: to the delight of neighbours who don't. "I don't suppose you've got a bolt like this John? It's erm ....... for the stocks in the cellar.. She keeps escaping....."
DD of course hand carves his self tappers from Unobtainium billet sourced from the planet Pandora by 8 feet tall blue people who fly dragons and stuff and using state of the art intricate dental tools, lubricated by the tears of .......
The Most High and Sacred Teething Infants of Burkina Faso Convent Orphanage.
On the days when he just can't be bovvvered. Other times, he pays more attention to detail.