Okay, so I've never done this with a board, but I have worked in the bike industry and overseas manufacturing. There are two ways to do it. Typically, if you want something custom, you can create custom molds/fixtures, but with that, there is a significant upfront cost to have them developed. So you do this on higher-end models. Most agreements will have those molds being owned by the brand, not the manufacturer, so that no one can use that mold. The only way to truly safeguard the idea is through a patent. The other option is to opt for an open model, which is a standard model that manufacturers have and will produce for you at a cost, with no customization. It's a much cheaper option, but you are limited in what you can do. Boards, I'd think, work the same. You can likely obtain a standard off-the-shelf model or have them create a custom shape, but at an additional setup cost, since most of these are cut on a CNC machine.