Depending on the amount you need - I have used the Gougeon "Circle Templates" method while building R/C sailboats, as well as for small around-the-home projects.

Basically they are two circles drawn on paper with the proper diameters for the mix ratio 1:3 or 1:5. Placed under wax paper, the resin and hardner are pumped directly into the circles which means they are at the proper ratio. Just stir together and the mix is proper and offers a great cure. My most often used size is (approximately) a quarter sized hardener and a silver dollar sized resin. (both sizes are approximate). Once you have the circles drawn to size, a photo copier will enlarge or reduce to meet the volume needed.

This suggested mixing method was included in their EPOXYWORKS magazine.