Love your choice of colors. It's going to be so awesome no matter what color you use for the sashing.

Just a personal observation. I really like the black sashing if you want a simple sashing. It makes the blocks stand out with their beautiful primary colors. I also like the idea of the shadow effect. It would make the lovely primary color blocks pop out and that would be very nice. I did that on a quilt for a grandson that had trucks on it. It was a really fun quilt.

Wood grain fabric, like the floor, would look awesome.

I still haven't ruled out the solid black..it would be easy and his birthday is 3 weeks away. However, I'll machine quilt it with a walking foot, so it isn't really much of a time crunch at all. I want the quilt to be something that he can carry with him to outdoor concerts and festivals, so want it tough. I'm doing 3/8" seams instead of 1/4" for a little extra strength too. The wood colored fabric sounds interesting and I'll have to try that option out when I go hunting...I have to get a backing for it anyway, so a shopping trip is in order. Thanks again for the ideas! Keep them coming!

What ever you choose, it till be lovely.

Ok, I dug though my stash and came up with some examples. So far, I like the black the best with the orange coming a close second. I know I'm limited to seeing the shade that I have them on, so the purple or gray might be better in a different hue. I don't care for the brown, but it is sort of a pinky mocha and it really needs more of a yellow tone to look right. Opinions???

I really think the black sets off the pinwheels so nicely.

I think black sashing with primary colored cornerstones would look great. Maybe a thin colored border before you add the black border.The thin border could be made of the small strips of fabrics you used in the pinwheel blocks.

I love the fabric in your blocks. I think the brown in between would look ok, because you have the blocks on the floor and it looks good that way. The shadow effect sounds awesome to me too.

I'm really wanting to do something besides black...you know how black picks up every piece of lint and string in a house and proudly displays it for all to see. (he's a 25 year old musician and I'm not sure how much a vacuum cleaner gets used) I can see where a trip to the store is in order...and I'm leaning toward something wood colored with an orangy cast...and the gray is growing on me too. (with a black sashing and a red narrow band for the gray) Keep the suggestions coming. I'll post more as I get ideas.