A Valheim sundial may be just the kind of creation you didn't know you needed until you saw it, and all you need to make your own is a pile of wood. Also the sun, but hopefully that isn't a problem.
Reddit user civalry80 posted several screenshots of their design to the Valheim subreddit, explaining that they built a sundial to confirm that their Viking squad is "always leaving the base just before dark." As someone who tries to only go out in the day as much as possible - my main base is in the Black Forest and one can only slaughter so many greydwarves before whatever errand they were on no longer seems worth the hassle - this looks very useful.
There's no mechanical trickery or modding at work here, just the steady movement of the sun (and moon, which also produces shadows) through the sky. Granted, you could just look up to see roughly what time it is based on how close the sun is to the eastern or western horizon, but this sundial gives you much more precision at a glance. It's the best in-game timepiece we're going to get unless Iron Gate Studio starts letting us craft Viking cuckoo clocks at our workbenches - and Valheim is in early access, so we can't rule it out.
They may not be quite as practical as inventions go, but other players are earning some serious in-game architecture points with the likes of a Valheim pachinko board, and even a recreation of the Notre Dame cathedral.
But who needs to build a wooden sundial when you can use a Valheim mod to tame a troll and simply observe where their massive shadow falls?
Valheim tips | Valheim workbench | Valheim repair | Valheim seeds | Valheim merchant | Valheim biomes | Valheim roadmap | Best Valheim weapons | Valheim Game Pass | Valheim Elder summon | Valheim cheats and spawn item list | Best Valheim armor | Valheim Bonemass | Valheim flint | Valheim crafting progression | How to plant seeds in Valheim | How to tame boars in Valheim | Valheim barley and flax | Valheim Black Metal | Valheim silver | Valheim Ymir Flesh | Valheim Moder | Valheim Yagluth