No, actually the standard Smooth-on container is a wide mouth (~1 1/2 inch) jar. Stop by the local Hobby Lobby (thats where I got mine) or pharmacy and buy some measuring cups (30 - 50 ml /1 - 1 1/2 oz). Smooth-on mixes 1:1. I use 2 different cups (mark them A & B) to measure and mix in a plastic bathroom cup. I grabbed a bunch of stirrer sticks from the coffee mess at work. Do not mix up the 2 measuring cups. Once you have poured the material out into a cup - never pour it back into the bottle if you poured too much. Just waste it. Contamination WILL occur and the whole bottle will harden (not immediately, but while in storage).
Once open, seal the remaining stuff in the jars with some wax paper & tighten the lids tightly to prevent air from getting in. If you don't use the wax paper the lid on the yellow container will fuse to the jar. I'm keeping my left-over rubber & resin in the refrigerator to help extend its shelf life. (I make batches of small parts - I may use a few ounces now and not use it again for a few months). Take it out of the refrigerator a few hours before use to warm to room temperature before using. Although the chemical reaction is exothermic (i.e. it generates heat) the cold materials really slow down the setting time.
Standard domestic protection instructions apply. Don't use the wife/girlfriend/mother/SO's kitchen stuff to measure, mix, & pour. Protect the kitchen table/work surface from spills. It does smell a bit but is not overly offensive.
Before you commit your master to rubber, mix a trial batch & see how it behaves. Then make your mold. Before you cast your first parts, mix the resin & see how it behaves, how much free time you have, and what happens when the resin starts to kick