The craft train upcycles tin cans and turns them into a mini golf course. She adds flags and includes a free printable template. She even makes golf clubs out of paper towel tubes and duct tape. Make sure to tape the can to avoid sharp edges.
Good for ages 8 and up.
http://www.thecrafttrain.com/1/post/2013/05/tin-can-indoor-golf-fun-from-recycled-junk.html
Inner child fun uses carpet and cardboard.
Get the instructions here:
http://innerchildfun.com/2012/01/carpet-golf.html
Repeat crafter me folds up a green towel.
Get the instructions here:
http://www.repeatcrafterme.com/2012/03/diy-putting-green.html