I’ve been doing some research towards making enclosures for the Round 6 AudioMoths that we have on order. For the benefit of others, here is a bit of a summary of some of the attempts that I've seen so far:
(1) a zip-lock bag (the ‘base model’). This is rain-shower-proof (but not fully weatherproof, I don't think) and the sound recording doesn't seem to be affected by the thin plastic over the microphone. Simple, cheap, lightweight.
(2) a little click-lock container with a hole drilled in it for the microphone to listen out through, and some Scotch tape over the hole. In this example the container wasn't watertight to begin with. https://www.openacousticdevices.info/support/enclosures/box-for-audiomoth
(3) using a click-lock container (with a drilled hole) and some clingwrap over the hole. Not certain how waterproof the end result of this was. https://www.openacousticdevices.info/support/enclosures/an-alternative-case-for-audio-moth
(4) using an electrical junction box (with a drilled hole) and some hydrophobic cloth. Still not fully waterproof. https://www.wildlabs.net/community/thread/554
(5) using an IP54 ( Ingress Protection: 5 = dust protected and 4 = splashing water protected... see https://en.wikipedia.org/wiki/IP_Code) electrical junction box (with a drilled hole) and waterproof acoustic membranes (stickers). I think I like this the best out of all of these because the boxes have moulded eye-holes such that you can attach with cable ties and it all sounds reasonably water-tight. But the stickers are really expensive and didn’t always hold-up in field conditions.
(6) adulterating a waterproof/dustproof case. This seems only a step or two short of putting a tiny detector in a shipping container for deployment. But it might be good if security is an issue. (I think I'm going for the if-I-hide-it-then-no-one-can-see-it-and-therefore-can't-steal-it approach.) https://sites.google.com/view/audiomoth/housings-or-cases/samson-case
(7) a custom 3D-printed case. Not sure how you print the rubber seal? Is that possible? Also not clear how the microphone has access to the outside world?
(8) the Open Acoustic Devices’ acrylic case. In the pipeline, it seems. See these threads:
While not a full solution, there was theoretical discussion to suggest the addition a ventilation port such that any condensation can evaporate out of the case. I don't know what to think about this. If the air holes faced down and were underneath some sort of sheath then it may work? Provided that the case was always mounted 'right side up'. But, presumably, this would also let humid air in? https://www.openacousticdevices.info/support/device-support/audiomoth-housing
I have also contemplated popping a desiccant in the case, just to keep things happy and dry (and to protect from condensation etc. on the inside if the case is in the cool, then the sun, then the rain, then the full sun again, then the cool etc.). Silica gel baggies seem simple and cheap and the way to go. This has been mentioned a few times in the support forum here too.
So, for our planned study (in south-western Australia – and the climate that we have here), in summary, I think we need to use an enclosure that: (i) is generally weather-resistant (i.e. rain and wind but not necessarily immersion; and we don’t experience frost, snow etc. or crazy, prolonged humidity either);
(ii) has loops through which cable-ties (or similar) can be threaded for securing the enclosure to a branch/stake etc.; (iii) has a hole through which the microphone can hear the outside world - but have this hole weather-proofed in some way. (I think this weather-proofing of the microphone port is where all the challenge is in any of the above systems).; (iv) is reasonably easily open-able such that we can get the AudioMoth units in and out without too much fuss (we’ll be doing this on a regular basis); (v) has enough room for a backup bag of desiccant on the inside; (vi) is cost- and time-effective to construct.
If anyone has any other input at this stage then it would be much appreciated. Otherwise, I’ll update you all when we decide on our approach.