Yup! Custom mods are available by e-mailing
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. Likely it will be Justin Polachek who answers. You just tell him what you have in mind, and he will tell you if it is possible, and if so, how much. Technically, there is not much more to it on your part, other than paying for it, of course!
I have used the process myself to get a quote on a custom job, and if everything works out, I will be going forward with it (hopefully) early in 2016.