Warning: I’m playing the experimentals, where some of the level prereqs differ from 0.B, so my advice may or may not apply to you.
If you’re looking for something to spam to level Construction, wooden doors look like the easiest spam from 3->4. Deconstruct a door in a doorway and keep rebuilding and deconstructing the door–each one takes 15 minutes, 4 two-by-fours, and 12 nails (you’ll only get some of the two-by-fours and nails back each time you take it apart), making it the quickest and the cheapest in wood. Failing that, you could do counters, but they take 20 minutes and more wood.
Other things that could get you skill XP from Construction 3->4, just in case you actually need any of these things: roofs, log walls, brick walls, beds (good to build if you’re in a building without one at the moment), armchairs, wooden kegs (for clean water, another piece I advise), Coolthulhu’s new charcoal kilns for mass charcoal production (also recommended), chain-link fences/posts/gates.
Once you hit level 4, to get to level 5, I’d say probably cupboards or lockers. Though there’s also reinforcing any boarded-up windows in your house, building windowframes, installing peepholes in your doors if you have peepholes to install, building palisade walls and gates, simple concrete walls, log and sod roofs, and also shallow water docks.[/quote]
Is there a way to make a normal wall? The only walls I can build don’t look like existing walls. I took down a door and wanted to put up a wall and did, but it looks completely different from the rest of the room.