It is now a reality - cost me 12 hours in the shop today. A full size version of my pencil shooter!
This is the most dangerous and effective slingshot I have ever build.
45 kg (100 lbs) of a draw weight means it propels the 115 Gramm (a half pound) aluminum bolt with a steel tip at scary speeds. This uses my effective arm range! I see no way of making it even more powerful.
I named it "Massacre Master" because that is what you can do with it - ten such monster bolts fired in under 10 seconds, easily.