You love Jello, right? And I bet you love those individually sized portions of Jello that make a great desert for your lunch, right? But, those pre-packaged cups aren't exactly cheep compared to a box of Jello. So here's what I do.
I buy individually portioned yogurt in cups with lids. Personally, I prefer Yoplait, but I'll suck it up for a week and eat the stuff with lids. Save the cups and wash them out with your dishes. You'll want 5 cups, so a week's worth of yogurt is all you'll have to suffer through. If you really don't like yogurt and don't live with someone who does, you can buy little reusable plastic containers about this size of 6oz yogurt cups.
One box of Jello will fill 2.5 6oz yogurt cups, so use two boxes of (sugar free) Jello. If you want them to be all one flavor, double the water quantities and follow the directions on the package. I use a 2-cup liquid measuring cup to mix Jello, I boil the first cup of water in the microwave, mix in the Jello and then run the tap until the water is cool enough for the second cup of water. Use a bigger measuring cup or a bowl with a pour lip to pour the Jello into the yogurt cups if you're doing one flavor.
To do two flavors, mix one packet of Jello as directed, fill each yogurt cup half-way, and set as directed. Once the cups are set, mix up your second flavor, pour on to the top-half of the cup. The flavors will blend gently, but not mix. The hot Jello will just melt the top layer of the original flavor.
For a fraction of the cost of the store-bought stuff, especially if you catch the Jello and yogurt on a super sale, you have great, custom made Jello for your lunch all summer. I tend to use my yogurt cups for a summer, and throw them out at the end of my Jello season, starting over again next summer.