I had my wife make me some from some Camo Material I purchased from Walmart. I wanted something light to carry since I also use them for Deer Hunting up in the stand during season.
So I designed the size of the bag to fit a large plastic bag of rice from the grocery store. Leaving the rice in the plastic bags placed the rice bags in the new shooting bags and had her sew them up. At the present they are three years old and going strong. I use them on my shooting bench as well as for hunting. It depends of course on how large and what dimension your bags are if this technique would work or not. I also can carry them very easily anywhere I want. I have a large shoestring with a cinch loop on each end. I simply place the the first bag in the middle of the loop and cinch it snug. Put one on the other bag and hang them over my shoulder or around my neck when carrying or climbing up into the stand.
Inexpensive and works well. Some guys also do the same with a bag of beans from the grocery! I could have had my wife sew short straps with rings on each of the bags and had a strap with a snap hook on each end. Maybe next time!