It's not something I would do. I have found that having at least one of each kit that I am prepared to make, made up in what I consider a cracking blank and letting the clients see them, if they see a pen they like they can either buy it or commission one similar to their spec, a commission is of course more expensive


You can try PSI and use their Pen Design Studio, you can make up all their kits in whatever blanks they have.
Peter