If it's measuring conditions inside, you don't need to put it in anything since it already includes an enclosure. If you wanted to put it in something as an enclosure, I would recommend the BME280 and a simple container like a contact lens box with holes or similar. These are low voltage devices so the enclosure isn't important. Being that it's a DHT, you could just put it on the side with sticky tape. Then again, since you opted for the model with the extra board, you will probably want to figure something to hide that. It would be easiest if you desoldered the board and put some leads on it such that the board went inside and just heat shrink/electrical tape the exposed contacts where the leads were soldered on.