The Financial Constraints
I don’t have money to spend on this project so expensive parts are out of the question. Most of the sensors are from China, 99p($1.00), but it can take a month or two to get here.
Eric’s size is limited by his environment, if he is too big he will become an obstacle for the other life forms and as a result may sustain damage from collisions. Another factor is cost, bigger pieces cost more. On the other hand, if Eric is too small he could be accidentally crushed underfoot. The ideal size is the same footprint as a person standing, around a foot square.
“You know, a little nibble here and a little nibble there, Lister, and before you know it we’re flying *backwards*.”
Another design problem is the cat.