The new Hidden Side fire truck was my favorite Hidden Side set to design so far! With it releasing soon, I thought it would be cool to share some of my process on this set. Here are my initial quick sketches from January 2019. #LEGO 
First off, some development pics on the truck. This is the first version I built of this final direction we ended up going with. It showed a lot of potential to make for a fantastic toy. Sadly, there was an incredible amount of structural issues to resolve.
A mech on the back meant very little space for the structure for the wheels. If a kid were to push down on the truck with all their might, it could not buckle. The back also had to look good without the mech. On the final set you can see how I tried my best to fill all the space.
With the structure on the truck figured out, I faced a lot of challenges with the mech legs. For the transformation it needs knees. So I built a stop for them to rest. The build had to be changed drastically as the long term testing showed that they were a crucial weak point.
This is the last one of one of those tests. As you can see, this is pretty close to the final version. Because we were testing the functionality, the colors did not matter as much. So I had some fun making an M-Tron version. The lower leg design was changed to be more robust.
Speaking of colors, very late in the process we shortly considered dark red. I know it's weird, but I am happy we didn't. The design language for Hidden Side was something I am very involved in and keeping the good guy vehicles bright colors is important in tying them together.
This set was probably the hardest Hidden Side set for me to design. With the new direction for the story and the app and the inherent complexity of this as a toy, having to balance this many factors was mind boggling. At times I had no idea if we could pull this off.
Evidently, we did! I am extremely happy with the amount of fun I managed to pack into this set. I'll do another thread on Nehmaar Reem, the Harbinger.
Lol, you can see by the space that I had to copy paste that name. He was not called that when I was designing him. :p
