I'm going to be replicating Optimus Prime's head and was thinking about using RKT covered with fondant. I've only worked with RKT one other time before, and didn't like the way bumps appeared (probably because I didn't smooth it out enough or maybe my fondant was too thin), but I was wondering if anyone can offer any advice or suggestions before I start this, what's beginning to feel like, a daunting task. Thank you for any suggestions you can offer.

Make sure you pack the RKT really tight together as you mold it into the shape you want. I mold mine, I don't carve it like I would a block of cake. Some other CC-ers suggest breaking up the RK themselves into smaller pieces before adding them to the melted marshmallow.

I've only iced my RKT sculpters in royal icing thus far, but I've read others say they do a think crumb coat to help the fondant stick better.

Thank you so much! Wish me luck.

What's the shelf life once it's covered? It's being consumed, so just curious how soon I should start making it.