I need to turn a bedroom into a playroom with a place, (shelving.)

Use plastic crated zip-tied together and stackable

Turn book cases on its side for storage..

I would use shelves similar to these with smaller baskets so the children can organize and put away toys when they are done with them. They would be inexpensive and help with the clean up .

lol The 7 year old's eye level got me. I'm a mom of 4 very grown children and I tried so many things to get them to be "neater" it is a battle my friend. I had storage containers, I even put a peg board wall in my daughters room once because when we were at Walmart she always straightened the toys out! It did not work. I decided to ask them how they could help themselves be neater so mom could do her job (sweep, mop, dust and vacuum) easier and it was like a light went on in their little brains. Even though they saw me doing it I don't think it registered that it was my job. They got better after that. My favorite line involving the raising of children is "Don't take it personally." they are not intentionally trying to make your life miserable or plotting against you. They are little humans finding their way in this world like we all are. They don't know a lot of stuff yet so give them all the tools you can (sympathy, compassion, awareness come to mind). Sorry for babbling so much. I just love kids and it's such a hard job raising them but worth it.

You could do pallet crates - attach a few of them together