Discussion and questions related to the course Engine Building Fundamentals
would like to know which tool they advise to weigh the components of an engine such as pistons, connecting rods, etc.
I'd recommend something like this - http://www.jegs.com/p/Proform/Proform-Digital-Scales/748209/10002/-1
There are cheaper scales available but you're likely to struggle with repeatability. Even the scales I've linked to are quite cheap when it comes to precision scales. You'll want to look for scales that can weigh at least 2kg and measure down to 0.1 g.