Hey Quigs, have you seen the Terrox? It looks like it's got some of your Busbox happening in it too. Sorry OP, non-retractable.
Really??, I mean come on...Gutten Tag, I am lead machinist at the
Maybach USA factory and built this during my coffee break...I'd love to see him bang that off using a Dremel and a glue gun...ok, it's serious cool but so demoralizing
Ok rant over, oh and thanks TC, at least I didn't have to hunt to ruin my day, you served it up for me

...another idea I tinkered with on the retractable atty is to mount the atty con on the blade holder of one of those cheap retractable blade box cutters (you know the ones that can lock) and power it with a piece of 18 awg coiled cable from a 12v car charger...the box is slotted so that the thumb slider/lock is accessible...it'd be kinda gimmicky plus I thought why would you ever want to have more than the drip tip sticking out?...which lead me to my typical recessed atty's designs
Edit: sorry OP, you said automatic...about the only thing I can think of aside from a long
throw selenoid or servo would be to try the spring loaded catch system from one of those kids "plunker" dart guns...which might be kinda cool (and easily weaponized

)