I read about using a life vest for a weighted vest. I gave it a try. Used sport stores are the best resource for a vest, under $5 is easy to find. Look for the jacket with the most separate chambers; it keeps the sand from shifting. Use shortest cuts that will enable you to remove the foam from the vest. Use duct tape to reinforce the seams before you sew. I was able to get 40 lbs. in mine. I left the foam around the shoulders and upper back.

Good Luck,

aaron