There do seem to be quite a few skills which don't trigger associated quests which is a shame, as it would be lovely to have quests that explain the benefits of the skills and demonstrate what you can do with them.
With tinkering 4 + engineering you can craft tools, but you need metal ingots, so you have to know alchemy 2 or you can get some at the actions.
after engineering you can learn blockmaking, buy the parts at the hardware vendor and build a block making machine. soil appreciation comes handy, because otherwise is hard to get loam.
tool crafting is a bit of a letdown, as the resources required to make the expensive ones are significant and because they are so easy to purchase from vendors.
i got excited about the ability to craft tools too, just like you, but in practice the skill gets extremely limited use considering it's long learn time.
regarding auctions, the market is already flooded due to the vendors, and the resource and energy requirements are high enough that you can't undercut the vendors by much and even if you did, other activities are far more profitable.
It's a shame, I hope they find a way to make crafting more fun, like having the ability to make unique or non-purchasable tools, like a pick that consume less energy or is faster but gets less chunk, or just something different that make it worth leveling up those skills, it would benefit the market too, I think.