Hello,
I would love to help you with this. I'm a mechanical engineer and I'm ready to take this task. If you are confident it can be done in three days and I will do it, and if you say $40, I say $30, not because I'm not sure of my work, but because I need good reviews on my engineer work here (I only have reviews with the other thing I do)
Thanks for reading my proposal
Have a nice day :)