Core design
Quotes are verbatim and attributed to their original authors.
The wooden core is the backbone of the ski, and its thickness profile is the single biggest lever on flex. Core design is mostly about choosing that profile, the wood layout, and where to reinforce — and, for a first build, keeping it simple.
Finding a thickness profile
The most reliable way to a target flex is to reverse-engineer a ski or board you already like:
As a rough anchor, forum snowboard cores run around 6.25–7.5 mm underfoot for a mid-size board with 22 oz glass (9 mm is "stiff as a board"), tapering to the tip-spacer thickness (~2 mm) at the ends; skis are commonly in the 11–13 mm range underfoot (see Core profiling for the 2-12-2 shorthand).
Wood layout and inserts
A typical core is a light field wood (poplar/aspen) with harder stringers along the edges and under the binding inserts (maple, ash) for screw retention and durability — see Core wood selection. Snowboard inserts are set into the core and ground flush.
Keep it simple first
The strongest recurring advice is to resist copying the "features" of consumer boards on an early build:
Or, more bluntly: "Keep it simple at the beginning" (gav wa). Cork inlays, aluminium channels, and exotic mixes can come once the basic recipe is dialled.