Create a bed skirt out of out of goal netting, if your basement has a bedroom area. You can attach the netting to a colored background to bring out the white, or simply attach the top to a piece of fabric to keep it in place under the mattress.
Create a sports banner door cover out of fabric. You can divide it into slits so it opens like a bead door, or leave it as one piece.
Add wall decals related to your son’s favorite sports, or have photos enlarged and printed onto posters or wallpaper.
Install a goal, net or end zone on the wall for the kids to play with.
Sew pillows in the shape of sports equipment such as balls, helmets and sneakers.