there are many ways to have nice metal inlays in wood, on something like a kayak try to use the thinner material you can find if its sheet metal, you can find stuff as thin as aluminum foil in copper or brass. The method of working those depends on the material you find but as said use the real thin stuff as onlay.
If the sheet is thick youd be using a jeweller saw (or a metal blade in a scroll saw, but a jeweller saw is adjustable in width so you can use broken blades) to avoid breaking too many blades lubricate while cutting every so often using a little block of beeswax, after awhile youll feel in your hand when the blade needs a wax.
A piece of stock clamped on the bench with a keyhole.. hole in it will give support and freedom of movement.
Dont clean the edges of the inlay once cut, the barbs left by the saw will help you press the contour line in the wood, If you use the wire method to make your metal inlays the faster method is to hold the inlay in position and then using a welder to "burn" the contour in the wood heating up the inlay itself, since youre supposed to sand the whole surface with the inlay in after, the change in color isnt a problem. If your wire is round you can flatten it a bit with an hammer, otherwise be careful to leave it proud of the surface so you can sand it to a flat side. Angles left by kinks in the wires can be perfecly straightened clamping one end and pulling sharply at the other end (without breaking the wire).
Work the wood with a dremel tool kind if you use wires, or if you can find a jeweller or dentist drill even better.

If you need bits or blades etc dont go to hardware stores (or buy the dremel kind stuff) it will be a lot cheaper to visit a jeweller supplies store (or stores that have supplies for people that make dentures, the tools are exactly the same)