Bedroom decor for a scientifically inclined six year-old

Consider doing a wall (or even just the lower half of a wall) in chalkboard or whiteboard paint. Great place to draw pictures, write down ideas, do math problems, etc. I made a scale model of the solar system in 3rd grade and the planets happily lived staged around my room for years. I would have put glow in the dark star constellations on my ceiling but we had those horrible popcorn texture ceilings so I had to settle for just sticking them on my ceiling fan instead. If you go with the cloud theme for painting in the room, I actually think it may be required by law to put glow in the dark stars on the ceiling.

Give him a work bench that he is allowed to scuff and scratch and stain and get glue on and put holes in. If you aren't happy with him messing up the surface, buy a piece of sturdy replaceable material you can cut to size and put over the nice surface. Add a C-clamp or two for holding stuff in place. A light on a flexible arm so he can focus it on what he's doing. Two seats at his level, so he can work alone or with you. Add a suitable protective floor covering under it and the space his chair occupy. Make sure there are electrical outlets. Even if you think he's not ready for this stuff yet, make it the kind of place where a person theoretically could use a hammer, hand saw, drill, X-acto knife, glue, paint, soldering iron, etc., and you wouldn't freak out about the furniture. Imagine him eventually (by himself or with you) building plastic models (paint, glue, clamps, light), repainting all of his Matchbox cars, putting together a robot kit (paint, maybe soldering), building and painting a kite, building (never painting) a bird house (saw, hammer, drill), replacing a dead hard drive (box to store little parts, little screwdriver, good lighting), and so on. Some of this might be better done outside or in a garage, but it could be nice to have a warm place right in his room where you could keep an eye on him and work with him.

If he like circuits, you need to make a wall or area with different circuit paths painted with conductible ink, have some electric leads or batteries he can pin at one end of a circuit, or leads he can use to cross from one party to another, and some LEDs he can pin to the other, of your lines aren't too long the LEDs should run of watch batteries.

Is he a precise "collector" 6 year old, or a "let's blow things up" 6 year old? For a collector, a kiddie microscope seems pretty awesome, and you can build a table/desk area around that. Not exactly decorations, but pretty much screams science (and then you're SET for making slides out of random things, dishes of pond water, etc.). If there's a useful window, kiddie telescopes can also set the scene (and then you can put up star maps, have him design his OWN constellations out of glow stars, etc.) For "lets blow things up" - bigger more durable plastic beakers, dishes, etc, squeeze bottles, and a waterproof space. Maybe a "test zone" like mythbusters - caution tape, tarps on the floors whiteboard on the wall that he can draw on or that things can splatter on, etc. (Also, http://www.amazon.com/exec/obidos/ASIN/B000FCYGGC/metafilter-20/ref=nosim/ are your friends. Nearly every wet lab I've worked in relies on them, and they really do make your life great.) For either, a piece of furniture that lets him organize his stuff - maybe even repurposed from Lego stuff. Lots of spacers/bins,etc that he can label himself. Science is all about making things from various shelves/boxes/bins of equipment! And absolutely mandatory - a big "Warning: Experiments in Progress" or "Experimental Test Zone" or biohazard (or radiation) sign either for the door or for the walls.

Oooh, ooh please please do think about assembling a giant pegboard wall with space for collections and things! I would have killed a sibling happily for a huge re-arrangeable wall with shelves and boxes and hooks where I could put my collections of rocks and books and weird things I found up, and you could run a long bench under it as a working "lab table". I put all my kid's toys in storage and gave her two rotating boxes that she refills every week or so, and her play area is much more open space and easy to tidy up for the next play time, and she gets all excited about a toy she hasn't seen for a month. It's less stressful than having everything on display. I also had for a while (and need to bring back, I loved this thing) a nature basket which was a blog idea - you have a beautiful bowl or basket on a coffeetable and put things you find on walks there, interesting sticks, beetle shells, rocks etc., emptying out or using up the older items as you go.

Consider doing a wall (or even just the lower half of a wall) in chalkboard or whiteboard paint. You can DIY a 4x8' piece of the wall with what is basically a white board for about $40. https://www.flickr.com/photos/iamthebestartist/sets/72157607082681113 and it's terrific. If you're fancy you could make it on rolling wheels with a three panel fold-out so that you could have a room divider and a place for your kid to write stuff down. But just a nice big white board and a huge variety of markers is a great thing to play with.

I get a lot of mileage out of a thing I call the "homeschooling cupboard," which is a cheap kitchen pantry thing stuffed with science kits, collections of interesting non-fiction books, craft project stuff, workbooks, whatever weird stuff I crammed in and forgot, etc. "Go check the cupboard" is a good answer to "I'm bored." 95% of what's in there was obtained cheap at thrift stores.

Speaking of clouds, here are instructions for a DIY http://www.designrulz.com/product-design/2012/10/diy-clouds-night-light/. My first idea was a new quilt, but boy are they expensive. So maybe a solid color quilt with a few themed pillows. Depending on the type of closet he has, you could replace his closet doors with a http://www.thinkgeek.com/product/8a2f/, leaving more wall space for other posters. Does he like space? How about http://www.amazon.com/exec/obidos/ASIN/B000GL2FOM/metafilter-20/ref=nosim/, a http://www.amazon.com/exec/obidos/ASIN/B001HQ1TRY/metafilter-20/ref=nosim/, a http://www.amazon.com/exec/obidos/ASIN/B000COQT0Y/metafilter-20/ref=nosim/, a http://www.amazon.com/exec/obidos/ASIN/B00EXJ6A62/metafilter-20/ref=nosim/, a http://www.amazon.com/exec/obidos/ASIN/B0016562O6/metafilter-20/ref=nosim/, or http://www.amazon.com/exec/obidos/ASIN/B00N2UBB3K/metafilter-20/ref=nosim/. Or if he likes rockets, here's a http://www.amazon.com/exec/obidos/ASIN/B00FS90Q9S/metafilter-20/ref=nosim/ and a http://www.landofnod.com/blast-off-throw-pillow/f8100. Does he like http://www.amazon.com/exec/obidos/ASIN/B001BOIWJA/metafilter-20/ref=nosim/ or http://www.amazon.com/exec/obidos/ASIN/B000K12YPS/metafilter-20/ref=nosim/? You could probably find similar posters for other animals too.

http://store-xkcd-com.myshopify.com/products/up-goer-five-poster