Like design process of any product, design of pens also starts with “thoughts on paper” – hand sketches. A lot of line and/or color hand sketches. Sometimes it is best to disengage the brain (except for the part that controls hand movements) and let your pencil fly on paper following… following… heart or something that resides in heart area rather then head.
Of course, any “flying on paper” must at certain point lead to a design which will be not only beautiful, but also ergonomic and technologically make-able. And not just that, but it also must be strictly within targeted tooling and production costs. So, designing pens is a pleasure and a pain at the same time.