The most milage my two year old has got out of anything is a whiteboard easel and a ton of dry erase markers. When she was a little bit younger she would dance while she was scribbling, then tell me she drew a backpack, or a row, row, row your boat. Now we use a lot of canvass and water color paper and printer paper, but nothing in the world has ever got as much use as that whiteboard. And so much easier to clean up than any other art supplies ever. Just sit there with them until they're old enough not to put the markers in their mouth (redirect that). Bonus! You can cook or read or anything while they're engaged.
There's a sticky parenting trap. My kids are so much better behaved when they're kept engaged doing something most of the day. I have Rubbermaid shoeboxes with Science supplies (wires batteries motors from radio shack), craft supplies ($10 craft jar from hobby lobby-worth it... I wasn't sure it would be.) They don't even make stuff with either box half the time, just rummage through them like a sensory game, pulling stuff out and looking at it, a rubbermaid box of crayons and colored pencils. My kid was as young as yours when I bought a poster board to teach him scribbling. I have a whiteboard for the second kid, but the first kid got a single posterboard he scribbled on for almost a year. I started them on Hooked on Phonics and a tracing letters workbook before the age of two. That's why it's a sticky parenting decision because they say names such as "hothousing" when you teach your kids stuff too young, like maybe you shouldn't do it. But the kids do behave better when you keep them engaged and learning on and off every day.
Really, I had to teach my kids how to play. Initially I set up a group of toys and sat down beside them and read to myself, telling them to play. Surprisingly, kids are not born knowing how to entertain themselves, even with all the best toys. It's almost like the parent has to insist, at first. Just like anything else, a little each day and it becomes a habit. My kids are not great at playing every time, but really they're decent at entertaining themselves (at age five and two) in the playroom, in the yard, they even occassionally play a board game togeather without an adult playing. This takes good timing on when to pull it out (on a good day) and I sit nearby, reading a book to myself or something. Still I'm proud. And it's something I've worked toward teaching them. When my first kid was your kid's age he certainly did not know how to "go play". I don't know if you know that's something a parent gently and slowly teaches, at least I did. I was surprised to learn that kids didn't naturally do that without being trained to "go play". It's because the parents are the kids favorite toy, but you can teach them to like their other toys and games.
P.S. the posterboard for scribbling got more milage than coloring books at that age.
