Haha even more ghetto, this isn’t my method but sharing is caring take a plastic water bottle or any other plastic bottle that is clean. Make a cut in it to make it tall enough to hold some water about the size of a rockwool cube(which will be going in there), next put the pre soaked rockwool cube in the bottom take your cut dip it in whatever stuff you’re using then into the cube.
Then ya take some water put it in the bottom with the cube and squeeze bottom of the top half into that little bit with your cube so as if you’re sticking the plastic bottle back together and then just wait a few days it’s like a mini terrarium works a treat low budget