I have been told that coconut caves are the greatest, and I was in desperate need for some cheap caves for my kribs. So I went to the grocery store, and bought 1 coconut for 1.50$. With this coconut I was able to make 2 caves out of it. First I poked a hole in the top using a hammer and nail then drained out the coconut milk (into the sink or a glass if you want to drink it) then I cut it in half. My store sells the coconuts scored (cut almost in half) so I got a hammer and carfully tapped/hit the coconut until the score cracked then I pulled it apart, hammering as needed.
Once I got the coconut in 2 pieces I then took out the meat. You can do this with a spoon and keep it if you want to eat it. I then used a hammer and a wrench to "bash" out a cave entrance. It was very challenging not to make the cave entrance way huge. So I did it very slowly. Once I did this I boiled the coconuts for 15 minutes then changed the water, because it was brown. Then I boiled it for 30 minutes and changed the water. Then another 30 minutes changed the water then I boiled it for an hour then changed the water. Then I put them in the tank. I boiled them so much because they can leach tannin into your water and turn your water brown. This tannin may not come out for a while so dont be scared if your water turns brown a little bit after you put the cave in (my water did not turn brown because of the time I boiled it.)
I'm very impressed at how natural they look. It is okay to leave all the little "hairs" on the coconut on or off in your tank. I took the hairs of one and left them on another. I like the caves better with the hairs, it looks so natural. Also if you have snails, plecos, cories. they love to suck on the inside shell of the coconut.