For those who've made large (eg birthing) pools of Gunge/slime before, have you ever tried mixing en masse? So, adding most of/all the water, *then* the powder and mixing with 1 or 2 people?

Seems a bit high risk as powder could just clump and not work! But could save a lot of time

Yes, I used a paint mixed and a high powered drill so no problems. Best done fast and hot water though as it thickens as it cools.