Longstick's suggestion is also very good for avoiding problems down the road. Yes you can make them yourself, I am not gifted except when it comes to mechanical things. Let me know how you make out making them, maybe I'll be able to buy a pair from you. Just make sure you watch your weight.
You can also use Kettlebells, light ones at first. Look them up, I am 61 and can do get ups with a 35lbs. Kettlebell, just worked out yesterday with them. These will make you scary strong with out all the bulk muscles, only make sure you read the book and watch the CD. I had a hard time pulling back the 50 # recurve, so I started working out because I was slacking, and it made a big difference, not only was I aable to draw, but also hold for awhile.
Hope this helps