Project for the winter season

Hello everyone,

Now that winter is just around the corner and the nights in the well-heated workshop will soon be getting longer, I've been giving some thought to a possible winter project. Here's what I'm planning to do:
I want to build or create a rear bumper for my G3 Vari. Unfortunately, I don't have any experience with things like this. What's the best way to approach this? Where can I get tips, suggestions, plans, etc.?
What materials are needed?

Thank you in advance.

What exactly do you understand by the term 'rear bumper'?

So, it's basically a modified rear bumper that completes the look of my car! Something like a rear spoiler bumper.