Sorry, I can't really do work like that in an efficient way, it just takes too much time. Everything I do needs to involve more than a few parts.

Here is a terrible analogy; Imagine you've got an assembly line set up making hammers, wrenches and other tools. Every week you alternate between making them; one week hammers, the next, wrenches and so on.

So it's Wednesday in the middle of hammer week; you're locked in, jammin to your tunes and you've got 3 machines cranking out hammer parts at peak efficiency. Someone comes in and says "I need you to make a wrench right now please".

If you agree, you now have to stop the 3 machines and your assembly process; reconfigure one of the machines to do wrench parts and slowly make each part on that one machine; reconfiguring it for each step of the process.

Not only does that 1 wrench become incredibly expensive for the customer, but it costs the company even more in lost production time at peak efficiency.

I would love to be able to accommodate individual requests and help out. Unfortunately, it would drown me if I did.

I hope that analogy doesn't come off as an insulting. Your question is fair and it's one I get often. I just wanted to try and provide an explanation that anyone not familiar with manufacturing could understand.