Great idea and a great way to spend time with your grandson. And, hopefully, get him hooked on golf, and building clubs. there are a lot of options that can work. Driver choices could be the MA0266 STw in a 12 deg. or a L-Tech in the 13 or 15 deg. One thing to consider too is to start with a #3 wood, with even more loft and a club that you can build to a shorter playing length. Would be a little easier to hit, but I understand if a driver is too enticing to pass up. Tee it high and let it fly is something 11 year olds like to do. Just be sure to not make it too long in playing length. # 6 iron and wedge could be the STi or the L-Tech. Both are Ultra Game Improvement and wold be good to start him with. On the putter, our inexpensive AS1004 Accustie mallet in either color, black or white, wold be a great starter putter. Easy to line up, mallet style. Only reminders I give in building junior clubs is to be sure the clubs are not too long or too heavy. They can not develop good fundamentals if they are.