Prerequisites – for best success rates and best prices, you will need:

* A level 16 or higher gnome with…
* 154 or higher skill in Fletching
* 143 or higher skill in Tinkering
* 105 or higher Charisma

This is a three-part recipe. Each item is listed along with the vendor purchase price for characters with a high charisma.
Firewater (50 tinkering)
0.010p Flask of Water
0.062p Gnomish Spirits
total cost = 0.072p, sell back = 0.067p
Shaped Ashwood Recurve Bow (148 fletching)
see note Planing Tool have to buy once for 10.709p, but item is not consumed
0.010p Hemp Twine
15.749p Ashwood Bow Staff
total cost = 15.759p, sell back = 14.952p
Tinkered Catapult (135 tinkering)
15.759p Shaped Ashwood Recurve Bow as made above
0.072p Firewater as made above
1.049p Metal Twine
7.349p Gears
7.349p Sprockets
total cost = 31.578p, sell back = 38.095p
Net Profit per Successful Combine = 6.517p