I actually found a papercraft tutorial someone made, but used cardboard instead of paper (obviously xD). After glueing/taping it all together, I cut out the heart shape that I would be looking though, and then I covered the cube in lots of layers of paper mache. For the see-through heart, I went to a fabric store and found the correct color of pink, making sure it was mesh enough to see through, but still hide my face. To get it on and off, I had hinges on the bottom that could open up so I could put it on my head, and I'd tap them close. There was a helmet inside so that I could secure it to my head and make sure that it would stay off my shoulders.
If you have any specific questions, feel free to note me! I'll do my best to answer. xD