With the arrival of the first summer heat, as happens for some years now, the bats are back to hole up in the frame of one of the windows of my house.
This event reminded me that I had lying around a small pallet that I used to make a simple batbox with the materials I had at home.
Realize it was very simple. I just disassembled and reassembled the pallet with nails, cutting the boards to the desired length (screws would be better, but I didn't have the right length... ).
Once I mounted the bottom of batbox, I made the grooves to allow the bats to cling to. I mounted the thickness of 3 cm to create the interior space in which the bats can squeeze and edited the rest.
I'm sorry but I forgot to take some photos so you can't see all the steps :'(
For those who are interested, I attach an audio recording of the bats I did few months ago. The volume is quite low, you'll have to turn up the volume.