Your best bet to get your mom onboard is to start off with a simple featherweight. Those can be build for roughly 200 pounds (but can ramp up to several hundreds more if you choose higher grade parts) My father used to scoff at the notion I could build a combat robot when I first started untill I build a mobile platform and drove it around the yard. He became much more supportive as I kept researching and learning about the methods and techniques involved.