i mix the dye concentrate and soda ash in jars that i saved too (baby jars, jelly jars, etc).
then i dye FQs in zip lock bags.
if i'm dyeing 1-3 yards i use a wallpaper tray that people use to wet the wall paper before putting it on the wall. you could use planter boxes too just make sure they don't have drainage holes in the bottom.
if i'm dyeing 3-6 yards i use the big buckets that my clumping cat litter came in.
if i'm doing a multi colored mottled fabric i put the dye solution into squeeze bottles and do a direct application to the fabric instead of a dye bath.