I made these bulk bags actually as a gift, but I plan to make my own once the holiday chaos dies down.
You will need:
a sewing machine
new or used fabric (I used muslin because I found lots of it used)
shoelaces or string
Disclaimer: I am not a big sewer, so I'm explaining things in the way that makes the most sense to me. If you have questions, please ask!
You can make these bulks bags whatever size you want. I made three different sizes, with my medium-sized bag about 11inches wide and 14 inches long. Just decide how your going to use the bag and what size makes the most sense for you. Keep in mind that you'll be going in about a 1/4 inch on each side when you sew and about 2 1/2 inches at the top for the draw string.
Iron your fabric. Next fold the fabric (the folded edge will be the bottom of your bag). Make your desired measurements and cut! I find that using a light pencil and a craft measuring tape works best to mark the fabric.
Unfold the fabric and lay it out flat. I like to zigzag sew up the cut sides to reduce unraveling. Zigzag across the top of the bag. You can skip this step, but sewing the edges will make your bag more durable.
(This is another step you can skip, but I highly recommend doing it). Now fold over ONE SIDE of your bag at about 1/4 inch. Iron to flatten, pin, and sew. You will only do this to one side of the bag - the side that will have the string coming out at the top. This way you will have a finished look where the string comes out.
Fold your bag again, making sure that the side we sewed on step three with the finished edge is on the OUTSIDE. Pin both sides, leaving about 2 inches of space at the top of the finished side. This part depends on how thick your string is. You want to be able to lay the string at the top and fold over with enough room to sew. Now sew each side at about 1/4 inch. Again, make sure you stop at about 2 inches to the top on the side that has the finished edge. I decided to sew twice along the edges to ensure a strong hold. Once sewn, iron your seams flat as best you can.
You are basically done! Iron the seams and trim access thread. I decided to just knot each end of the shoelace. You could tie them together too.
Optional Embroider Step
I knew I wanted to embroider my bags, but I wasn't sure what to say. I thought it'd be cool to embroider specific items like 'coffee' for the smallest bag. In the end, I decided to just embroider 'bulk' on each bag.
If you have any questions, please ask! Happy crafting.
I figured out how to do the wheat stitch so that I could have wheat stalks on my bulk bags. I thought it turned out pretty well.