The journey of making your own skis begins with a tree. Where and at what point you begin your engagement with it depends on what resources you have available. Ideally, the relationship begins in the forest, where you can see the tree, meet the tree, understand where it is growing and how healthy it is. If you can’t access a woodlot, then the next best source would be a logger or a sawmill operator.
The type of tree you seek depends on which species live near you; traditionally, skis were made out of what was available. Here in Northern Minnesota we prefer to use birch. It is a light, flexible wood that carves easily and bends reliably well. The tree you are seeking (or board) is straight as an arrow, with no knots, and is in good health. I typically begin by purchasing logs of ideal quality and bring them to a sawmill and instruct the operator on how I want the boards cut.