> I made a master marked cup with a sharpie, using water for the scales. I
> did it I think tsp by tsp, marking around the cup as I went. The nice
> thing was that I could then simply pick up a paper cup, hold them side by
> side and mark the new cup for use quickly. Never ran into any problems
> with the calibration being so far off that the mix wouldn't kick or cure
> right.

I use two cups. Fill one with water and mark the level. Pour about half into the second and line them up side by side. Eyeball the differences in level and mark halfway between the two on the second cup and you have the 2:1 volume ratio