Like David, I used a Sticky Stuff pump for large layups when building my Long-EZ, but now that I only do small projects, I just use a triple beam scale. I picked an OHaus used in like new condition for $35. I tried the digital scales, but they are too "nervous", and I probably never had one that was good enough to trust. I totally trust the triple beam.
Like Larry, I like to put hardener and resin in dispensing bottles like sold for ketchup.
The triple beam has a knob/weight on the end that lets you zero out the scale for the common size plastic cup you like to mix with. If you stick with the same size container, you just have to do this once.
I keep a card near the scale that has resin and hardener mixing weights for all the batch sizes I will typically mix. With the triple beam, you start with the hardener, and set the weight down to the 0.1 g that you need, and then just dribble in the hardener while watching the beam end pointer until it rises up to the zero mark. There is no trying to remember the digital target and watching the numbers jump around. Just nice, well damped, movement up to the center as you add material.
After the hardener has been added, you just slide the pointers up to the total weight of hardener and resin, and dribble in resin until the beam pointer again reads zero and you are done.
Steve