So some background here for those who don't spend their days in tissue labs: tissues are sectioned in very thin (~5um) slices and put onto slides. At this point, they are uncolored. In order to see any tissue structures, you have to apply a stain to the slice. This is done by loading slides into a holder and dipping them into a series of different liquids. All stains have their own recipes, but it's not unusual to have something like this:

1. 5 minutes in distilled water 2. 2x 5 minutes in 70% ethanol 3. 5 minutes in 90% ethanol 4. 5 minutes in 100% ethanol 5. 10 minutes in stain #1 6. 3x dip in 100% ethanol 7. 10 minutes in stain #2 etc

so what labs usually have if they don't have an automated stainer is a long section of benchtop with a line of small glass or plastic buckets (kind of like small tupperware containers), each with a different fluid. The tech then uses a set of timers to move the slide holders from one to the other according to whatever recipe they're following. It's honestly not a terribly time-consuming process, you can do a lot of other stuff while you're in a five minute wash, and a little variability doesn't matter much (like if you're in a bucket for 5:10 instead of 5).

That all being said, an automated stainer is a super nice thing to have, because you get 40 minutes uninterrupted time to do other things instead of having to go move things around every couple of minutes. So a couple of hundred dollars for this 3d printer one might be really worth it!