Felt, sewing machine and general sewing supplies, Printable fabric sheets (optional)
Step 1 - Cut the felt
I found some grocery related clipart online and printed them onto printable fabric sheets. These are available at most craft stores. I used the sew-on ones but they also come in iron-on as well which might make their application a little quicker.
Step 2 - Sew the bag together
Seam the square and 2 rectangle pieces together at the sides. Then pin to the bottom rectangle and sew.
Pin the handles to the top of the bag. I measured in 2 inches from the side seams so that their location was consistent on both sides.
Step 4 - Finishing
Turn the bag right side out.
After I made my first bag I wondered how I could speed up the process so I decided to make one a little bit quicker by foregoing some of the steps. I cut and seamed the bag just like steps 1 and 2. However, I didn't bother turning down the top and seaming it nor did I double the layers of felt for the handles.
I left the bag "inside out" with exposed seams and quickly sewed the handles on the outside and it was done. It doesn't look quite as finished and fancy as my other one but it certainly does the trick and is really reminiscent of those re-usable store brand grocery bags.