Need skinnier OP's?
Months ago I bought some Richesons Semi-Hard Pastels, I didn't like them, but they came in this rubber packaging. Later I decided to try using the packaging as a mold for melted OP's. I used Mungyos, their cheaper and I like them as well as NeoPastels. Almost the same just a little softer. Melting Neopastels worked too, they just melt a little firmer.
It takes one stick of Mungyos and about the smallest piece that you can break off of another to fill one slot. I brushed Mineral Oil in the slots. The melting point is 146F, I used a toaster oven set it at about 175F, and it shuts off automatically. I melted them in these condiment aluminum cups I found at Walmart. I am just keeping the cups for a similar color the next time instead of cleaning them.
I put them in the freezer, and push them out of the mold, you need to let it break in half, their very long. If you get them too hot they might be more breakable sticks.
They work great! They get your hands dirty not too bad though, but I have thought about spraying them with Crystal Clear, an Acrylic Spray. I haven't tried it yet. Maybe some wax paper would do otherwise.
I store them in a Conte Crayon Box with out the insert. They are just a tad thicker than a Conte Crayon.
Have fun if you try it!