I keep finding uses for the mixing tubs found by the concrete supplies in home improvement stores. The smaller size is about 20x27 and about 5 inches deep. I have always used them as a mini potting bench and mix up my potting mix in the tub place the pot in the tub and pot away. Very little mess.  Last winter I was using them as a multi-pot saucer and tote. They hold 9 1 gallon pots and you can water with it acting as a small reservoir for water and you don’t have to be mopping and cleaning up after.  With 9 1 gallon in each tub, made it relatively easy for the shuffle inside and out.  Cups tend to be tippy in them just like as in storage bins, but I found if you get 3 inch diameter PVC pipe and chop saw them into around 3 inch length you can sit them lengthwise and put the cups in them to keep them from falling over, when you remove some of the cups you don’t have worry about the remaining toppling. 

  I use a very light mix up to one gal probably over ½ perlite and right now I have my 1 gals in the 6-pack trays which fit right in one of these tub for plunge bottom watering, which is very good if you let them dry out a little to much, as many mixes are hard to top water if they get a little dry. I have used them when I was away for a day or two as in hot weather I have to water everyday.   I just put an inch or so of water in the tub and they do fine.  If I am away I put them under a shed/carport  roof area that gets good light but protects the tub from filling up if it rains, which would be bad. I could drill some holes in the sides at the max level I want the water to be.   You can wash the dog in them, and they make a pretty damn good snow sled, although I personally need the larger size for that.  They are tough as hell and only about $5 each. 

http://www.homedepot.com/p/Plasgad-Medium-Mixing-Tub-887101A/202086173#.UjpVIKyW86Q

This looks very useful. Thanks.

This is a very good item to have around. I also used it to mix soil when I was mixing my own. Since I started using Fertilome UPM, no more mixing for me.

I also used this tub for watering newly up potted cuttings in the 32 oz clear cups. I watered from the bottom only using the holes I drilled in the
bottoms and sides of the cups by soaking in the tub for 3-5 mins. It helped with the fungus gnat issue.

I have two of them..they are mini duck ponds/water bowls for the ducks and chickens.   Speaking of tippy cups......the best suggestion I have ever got on this board came from Gene......he said to turn the cups over so the lid is the bottom....100% stable that way and works so much better.