The first one is just timber so you can put anything on it, I would recommend water based polyurethane. It is easy to use, fast drying and relatively odor free.
The second one probably already has a urethane coat on it, now that could be water base or solvent base. Luckily you can apply water base polyurethane over solvent urethane once it has fully cured you should be ok to seal them both with water based products.
Or you could get fancy and do some screen printing or take it to a place that has a flatbed UV printer and get custom graphics etc put on it.
I actually build snowboards and have applied and tested all the above methods
for the bare timber, do i need to primer first? or just finish it with polyurethane?
i plan on painting it first, can i use a waterbased paint? if so, does that need primer?
the prospect of having to buy a bunch of different paints and sealers isn’t exactly getting me excited. what kind of shop would i call to maybe do this for me?
@thisguyhere The top I sanded off the clear coat and applied an orange wood stain, then two coats of minwax water based spar varnish, added the vinyl decal, and then three more coats of the spar. I’ve got some clear glass frit I’m going to apply with spar for grip.
The bottom was skinned with blue/black kevlar/carbon fiber cloth. I had the giant gator decal on the bottom but had some issues with fit so I pulled it off. I’m going to finish it by wet sanding down to 2000 grit and then polishing with liquid polishing compound. The skinning isn’t on par with @Sender 's masterpieces but it’s serviceable.