proof required for projects

If i had made some projects which are like line follower, 4-wheel tracked robot, micromouse etc then i will mention the same in my resume. Suppose i have mentioned them as a category in my cv as:

"PERSONAL PROJECTS:
1. LINE FLLOWER
2. MICROMOUSE
3. OBSTACLE AVOIDING ROBOT
4. 4-WHEEL TRACKED ROBOT"

and also suppose that there are no competitions or events won for the same projects.
Then companies may ask the proof for the same. What should i have as a proof for that?