When I worked on the Lancair project we had a pump, It was quick on small batches but it took a lot of pumping on big ones. And the amount was always a guess.
In my shop where I fabricate parts I use a 5lb scale from office Depot (staples) for about 65 bucks and I have no intention to buy a pump, its faster for bigger batches I mostly use and amount is known automatically. You also need a cheap calculator which I set conveniently next to the scale, The measuring process is very simple.
Set it on grams, Weigh the precut cloth first (example 300 g) and you will need the same in the weight of the resin. I use Aeropoxy which mixes 100:27 so its
300:1.27= 236
Zero the scale with the cup on it, Put in 236 grams of resin then fill the rest with the hardener to get 300 grams total and you are done.
Oh yeah ,and not to forget the best trick to handle the epoxy, transfer it into those laundry detergent plastic bottles with the no drip spouts, works like a charm and you don’t have the epoxy dripping and running down the side.
George