I cut up the block of pencils and made it into a nice 1-inch board, as you can see in the image above. I had no idea how machinable it would be, so I decided to take all settings very conservative:

3mm flat and ballnose endmills   –   feedrate: 600 mm/s, 150 mm/s plunge   –   stepover: 40%   –   stepdown: 1mm

Milling was tediously slow, but since I only had one shot at this, I didn’t want to risk tearing the pencils (and graphite) apart. I didn’t time it, but I think total milling time was about eight(!) hours… In hindsight, I could have done it much faster, as it turned out the wood was pretty soft and forgiving.

It should now be apparent what I am trying to fabricate here, and some people have rightfully expressed concerns regarding the strength and usability of the slingshot. But rest assured, I designed this bad boy to feature an aluminium core. Unlike my previous slingshot though, I wanted the aluminium core to be completely hidden.

To this end, I milled the aluminium core and wooden framework and glued it all together.

That’s as far as I got today.