Harry's Paste Extruder

Remix of the Spritztruder by Kitemare, for i3 Rework. I also used a modified idler from the compact E3D extruder by Mak-a-Face. Modified to have better support for drive gear. Also uses typical herringbone gears from greg's accessible extruder, so hopefully is a bit easier to incorporate into existing systems. Also modified to fit larger capacity syringes - 30ml ones by Terumo (from eBay), have OD of 25mm and ID of 22.5mm.

I tested Kitemare's Spritztruder and found the gear ratio to be OK when using M221 s1 in marlin to set the extrusion multiplier as 1%. It's a bit of a bad fix, but works OK for now, and I'd rather this that fiddling around with lots of gears to get a better ratio. You also need to fit a thermister to avoid thermal errors - use m302 to allow cold extrudes.

**I haven't carried out much testing**, but wanted to share anyway. I'll be carrying out some more tests using a clay mix over the next few weeks. This is quite thick, so requires a really high pressure to pus