An embossing kit is an item you can easily sell online, in novelty stores or via ebay. It's cheap and simple to make, but it looks really nice, and sells easily. Your embossing kit will include "embossing powder", which you will make, "fusing ink", which you will make, and any old pen. The "embossing powder" is a mixture of 2 parts finely powdered resin to 1 part gold OR silver bronzing powder (depending on the color you want to produce). The "fusing ink" is 7 parts water, 1 part Caro syrup, 1/2 teaspoon of Lysol, and a drop or two of food coloring.
You'll have to include instructions in your kit, and it's best to just perform this experiment yourself and come up with your own directions in your own words. Write or draw whatever you want using the fusing ink (by dipping your old pen in it), then sprinkle the embossing powder over what you just wrote. Shake off any excess powder. Now, apply heat from an iron until the raised effect becomes visible. It's truly remarkable, and anyone who sees how this works will be a quick buyer for your $9.95 product.