5x5 Peg Solitaire. Print it out and it is ready to play. Just break off the peg, flip, and place.

To Make: Print directly with the stl, or open up the scad and modify (scale, change # of pegs, remove anti-warp bottom). The pegs are printed attached, which makes it easy to give as a gift.

There are two stl's, one for kids, and a bigger version for adults.

To Play: http://en.wikipedia.org/wiki/Peg_solitaire