Hello,
my name is Liliana, i have over 10 years of experience as a designer, and what i like most is illustrate, that's why i like this project.
Please, check my Freelancer portfolio to see some of the illustrations and cartoons i made similars to the robots on the link, in order to evaluate my work.
I can send you more samples, if you want to.
I use Illustrator for this kind of projects, i can deliver you the images as vector format, and also saved as any other web format you may need, like JPG or transparent PNG, for example.
I really like this projects and i made many projects like this one before, you can check that on my profile, and i would like to create originals, detailed and fun robot heads with fun elements.
I hope that we can work together, please, contact me if you have any questions, or if you want to see some more of my work.
Best regards.
Lili.