Half the sewing work is already done when you make a T-shirt dress for a little girl. That's because the T-shirt is pre-made and you only add the ruffled skirt. In this case you will complete the dress for a prototype and then make several more in each size from 2T through 6X. Depending upon whether you sell the dresses at an outlet or online, you must also have a distribution plan. This project will help you decide how to proceed with your idea, understand marketing costs and find a profit line.
Make a prototype dress. Sew a hem on both side edges of the ¼ yard fabric. Make a running stitch along one side and pull the material until it is ruffled. Ease the ruffles around the bottom on the T-shirt. Stitch the ends together. Sew the ruffled edge to the T-shirt. Pull out the running stitch. Repeat with each different color until there are three tiers of ruffles. The T-shirt is now a dress and also the prototype for the project.
Calculate the cost of the T-shirt and other materials. Calculate how long it took to make the shirt. Assign a per-hour labor cost and add that to the material cost. This is cost per item. Multiply that number by 2.5 and that is the retail cost before advertising and marketing space.
Determine how you will advertise your dress. Decide where you will market your garment. Take the cost of these two factors and decide how many dresses you need to make to make this profitable. That is your target production. Adjust your profit line but stay within comparable market prices.
When all of your advertising and outlets are in place, proceed with production. You must make many dresses in different sizes to be able to have a good selection. Decide if you will only market one variation of the garment. Each variation in color or embellishment must have an equal number of sizes prepared in advance of sales.
You may decide to hire seamstresses to help with production. Add their hourly wage to your cost and readjust the price per garment.