Make hatchets more abundant
Bridge building is hard enough already, hatchets shouldn't be a rarity.
In order to be successfully using Bridge Building, you essentially need the skill to be 80+, or have really good nerves. Also, it's a rather essential skill for a certain dungeon level, not to mention the several underground rivers. As it's rather hard already, it's merely adding insult to injury that hatchets are so cripplingly rare in the game. It's a common everyday tool, after all. If you are unlucky enough to lose your hatchet to an acid trap or something, you might end up having to scum for a long time just to get the tool, even though everything else would be in place.
There are, of course, multiple solutions to this, and mine would be:
a) simply make hatchets less rare. There's very little reason that they should be any rarer than axes, hammers, swords... Of course, this should then be balanced by not having a BB training machine back at Yrrigs's.
b) if hatchets need to be rare for some reason, make e.g. Yrrigs sell them in Terinyo. The price could be hefty enough for people not wanting to trade them back to him for a BB increase.
The main problem is that BB is a fun skill, but virtually unusable at the moment (too low skill in the early game when needed, lack of logs in late game when it could be used for convenience). More bridges!