What's the best way to crush malt if you don't have a mill at home?
How much malt would you venture to crush that way?
I'll answer with a method that you shouldn't use - don't use a coffee grinder. It's pretty obvious that you don't want to use a blade grinder, but I thought about using a burr grinder set to the coarsest setting to mildly crush my grains. Before doing so, though, I searched the web and all accounts I read basically said it's called a grinder and not a crusher for a reason. Don't use a coffee grinder to crush your grains. Even on the coarsest setting you'll still over-pulverize your grains and end up with tannin problems.
I have put malt in a 1 gallon ziplock bag and crushed it with a rolling pin.
I have done up to 5 pounds that way in the past. It was tough but it worked. I am sure efficiency suffered. Although, I never experienced any tannin issues from over crushing the hulls.
I have also used the bottom of a flat drinking glass. But that was just for a few ounces and pressing down on the malt with a glass seems scary as the glass can break in your hand. Probably not the best way.
One of my earlier attempts was to use a manual pasta maker in place of a crusher. First, I took out rollers and roughed and knurled them as much as possible using a couple files. Then I screwed it onto a board, removed the handle and attached an electric drill. Overall, it worked, and I went through a couple bags of grain with it (50kg total), but then it fell apart.