I have decided to have him build a simbot but how and what traits should i give him (he will have a midlife crisis)
You need to reach Level 10 of the Inventing Skill and have no active Skill Opportunities. Then you'll get a phone call with a chain Opportunity called "Master Invention". That's the one to make a Simbot. You need something like 1 Palladium, 10 Life Fruit, 100 pieces of Scrap, and a Life Core (it will be given to you after one of the steps is completed) - I can't remember what else. Or you could get one for 40,000 Lifetime Happiness Points.
This might help.
As for the traits, don't give him a midlife crisis. Send him Swimming, or into a Shower, or have him interact with water, then have someone "Reprogram" him (it's an interaction) to change traits. Then have the Sim repair him. You could make him the standard utility sim - Natural Cook, Handy, Neat, Angler and Green Thumb.