Our youngest has those natural inclinations, and it's especially difficult for him and for the rest of us because my husband, oldest son, and I are all exceptionally neat, organized, and clutter-free. This tends to make our youngest (8yo) feel like he doesn't fit in, and I hate that. We've struggled through some issues.
Here is what HAS worked. If I know that something truly is important to him, I don't mess with it. He has to keep it put away whenever he isn't using it (whatever "it" is), but I don't ever suggest getting rid of it. As for other things that tend to pile up, toys and such, we go through them together, making "keep," "donate," and "trash" piles. We volunteer at our church regularly throughout the summer, helping those in need, so he has a clear understanding of those less fortunate than we are, so he is willing to give away toys he hasn't played with in awhile. I just have to start the process. We do this every season, so four times a year. After we've made the piles, he goes with me to take them to the church to donate, or to the trash if the toys are to much of a mess to give away. It's a good experience for him each time.
As for school projects and art creations, he can put whatever he wants on the fridge, or on a bulletin board, but it can't be over-crowded. If it's full and he wants to put something up, then he must choose something to take down and throw it away before he can put something up. I take pictures of big school projects and save them on a file on my computer. I don't print them out. He also has a camera, so he takes pictures of creations he loves. This has worked very well for us.
As for art supplies, well, that's something we do have tons of. Our oldest son is almost 15, and we've learned that kids do TONS of projects. I'm a teacher, too, so I need supplies from time to time as well, although I prefer computer projects. We have a cabinet in the kitchen dedicated to storing art supplies. Both boys know they can go there anytime they need/want to work on an art project. I don't allow them to save scrap paper, though. They must recycle that.
The only thing we still struggle with as far as our youngest is concerned (with clutter) is what to do with all of the Legos. I swear our house is being taken over by Legos! I love that he is so into Legos; it inspires such creativity, but OMG, there are so many Legos in my house! We have them fairly well contained on bookcases and in containers in his room. He takes them out and brings them into the living room to play with them every single day (he wants to be where we are, and I love that), but he is good about putting them away. He's getting more Legos for Christmas, though, and I don't know where we will put them. I'm sure we'll figure it out, but wow, there are a lot of Legos.
Sorry this got so long. I hope it helps some. :)