First, I don't consider this a toy, but rather a tool for a hobby. A toy you play with. This, you put rocks in a barrel and leave it alone to do it's job.But, it is a great tool. I got it for my girlfriend for Christmas. It caught me off guard when she said she wanted one, but I figured what the heck, why not. Now, almost 3 months after Christmas I'm finally writing a review. Why the delay? Because it takes a long time to finish the job.Her first batch was with a bunch of various rocks we bought from another vendor. They looked just like a bunch of rocks, nothing fancy at all. Well, after about a week in the course grit, you could see these rock were going to look really nice. In time. All in all, the rocks went through various levels of grit, and finally polish, and came out with some very nice looking polished stones. The next step is to make some jewelry with some of the nicer ones. It's hard to believe the difference in what a plain looking rock looks like after several weeks of being ground down, smoothed and then polished.Before her first batch was done, I decided I wanted to try some, too (a good reason to buy the two barrel model). I bought a couple pounds of Apache Tears. Well, after almost seven weeks, I took them out this past weekend. I found out after I started them, that Apache Tears are not easy to smooth and polish, but I'd already started them by then, so I was going to see it through. Wow, did they turn out great!I do wish some of the instructions had been a bit clearer though. You need to oil the unit, but the instructions left me, at least, not sure exactly where and how to do so. Be careful when you oil it not to get any oil on the drums or rollers. The lids are a bit of a bear to get on and off until you figure it out, and perhaps there could have been better directions on those as well.If you are going to get one of these, and you plan on doing two batches of rocks at a time, I would suggest you buy another drum, so you have at least three. Keep one for nothing but the polish stage, so you don't run the risk of contamination of the polish with some of the grit. A very thorough cleaning may alleviate that problem, but with the time it takes to complete a batch, the cost of a new barrel is negligible to ensure no problems. I actually bought two more barrels and use a different barrel for each stage. Mark them with a silver permanent marker (lids too) and you're good to go.(Remember, too, this set is not a kit. You will need to buy the grit and polish separate.)Although young kids will enjoy this, I still don't consider it a toy.