I am not a creative person naturally, but I can be resourceful. I got most of my inspiration from the Super Awesome Lego Party. They even made the mold which they used to make the soaps! I certainly didn't have the gumption to make my own molds, so I purchased ice cube trays made by LEGO.
Since I wanted my crayons to be solid colors that would resemble real LEGO bricks, I placed each color crayon in its own tin can (which my wonderful husband pulled out of the recycling bin and washed for me -- thanks!). After I determined about how many melted crayons it would take to fill the mold, I melted those crayons in the cans in the oven. I then simply poured the melted wax into the molds and let it cool. Since the ice cube tray is made from silicone, I was able to push the crayons out after they cooled. I made enough crayons for each guest to have some in their goody bag and to color LEGO coloring sheets at the party.
The LEGO shaped soap turned out surprisingly easy. I have never made soap, and so the idea of making soap sounded difficult to me. It was actually easier than the crayons! I bought some melt-and-pour glycerin soap and some soap coloring at Hobby Lobby. It was so simple; I just popped some cubes into a glass measuring cup, microwaved them until melted, added the color, and poured into the mold.
The soap cooled within an hour, and popped out of the molds with little effort. The soap left no noticeable residue in the molds, so I didn't even wipe them out between colors.
As I was bagging them up for the party favors, my birthday boy suggested that we cut them into other LEGO brick shaped pieces. I wasn't sure how it would work, but I tried it and it worked great. The soap cuts easily with a sharp knife, and the different shaped pieces made the bricks resemble real LEGO bricks more.