Well unless you plan to return painting within 24 hours, it's not the best solution for the price. Firstly the sponge will rot once bacteria gets inside, and it will. Figuring I was at fault, I purchased several spare sponges and a lifetime supply of palette paper to fit this unit. I recently threw out the last sponge.
Mold is also an issue which may be a sign that air quality in my home isn't the greatest? Some said to add vinegar to the sponge to prevent it. Others said bleach. I tried them all without much success. It seems I take too long to return to my projects! Weeks! Not only that, but what if you have more than one painting going on at the same time? I even "borrowed" the one I bought for my husband (a Christmas gift which failed to encourage him to express himself with paint.) for use with the second project I started. Both have either dried out or mold took hold.
Nevertheless, the palette paper is reusable and can be gently washed. There will be stain residue however and so you lose the pristine white background in which to judge your colours. If you find the refill paper too costly, parchment paper works. I've even purchased those smaller plastic 6 well dollar store palettes which separate the paint better and crammed them inside with some success. Just don't forget which side is up! Otherwise you have quite a mess on your hands. That's with heavy body paints too! They will in time slide...
The lid is not very user friendly until you learn to place it so that the tabs do not line up. For the price, I think a thin dollar store resealable plastic tub, with some folded paper towel as the "sponge" covered with parchment paper will work equally well. Neither solution will transport well as turning it on its side spells disaster as I've already mentioned.
I'm sure this works for some, but I do not recommend this product for artists who don't get around to painting as often as they'd like. I think Golden's Open Acrylics would be a wiser choice or save your money and use the dollar store version listed above. Sorry to sound so negative but I've stopped using it BECAUSE I was wasting paint. I give it 3 stars.
Here's a video link on how to assemble your own for a lot less money.