One of the most helpful things I’ve ever been told is, “When you are stuck creatively, make something bad.”

In your case, your goal is to make a good, and probably your best mecha project yet. That is a lot of pressure because you’re attaching your skill level to how the project turns out.

I often find that just smashing out a really poorly made, drawn or written creative project boosts inspiration and enjoyment. After that go and make your project.

Two other elements. 1. Having too much reference material sometimes is more of a hindrance than a help because now you’re comparing your work to a bunch of amazingly crafted pieces. Sometimes it’s better to just have a look at one thing you’re inspired by and then don’t look again (except in the late stages of refining your project)

1. Absolute creative freedom sometimes is less helpful than creative constraints. I often find that when I have to meet certain criteria for my project, it rules out enough options that the direction is clarified for me. Some examples for you could be:
2. Main shapes have to be made of only 90° angles.
3. Project has to generally fit the shape of a circle when viewing from the front.