First of all...great idea, would be watching a project like this with great interest.
Anyway, answering your question(s) is a bit difficult...
- What is your skillset? Do you have any experience with metal and/ or woodworking, molding/ casting, electronics etc....do you intend to expand your skills?
- What tools do you have on hand?
- Do you plan to (scratch-)build everything with the addition of using found parts or do you eventually want to incorporate 3D printed parts as well?
- Do you have a timeframe?
- What is your budget?
-...
EDIT***
Just read that you started to think about what real world items to incorporate into the build, good start!
My advice:
Answer yourself these questions and get an idea about what is actually involved in a project of this size/ complexity.
Search the internet for all available pictures of the probe droid and possible information about the way the original prop has been built.
Do some drawings/ scaling/ figure out the design and -again- match the results with the tools, materials etc. you have access to.
Then return and ask more specific questions about how to proceed.
Good luck !:thumbsup