A good use for scrap materials
When I take the roof off a hive I always look inside to see what is there. You can often tell a bit about the state of things, e.g. if there are woodlice they like it damp, so perhaps the roof leaks, spiders like the dry. There are often creatures such as moths, shield bugs and beetles. They are always worth looking at. Later in the season there may be the odd crysallis.
I have always been interested in wildlife and I am rarely without my camera. Most of the hives I see are away from dwellings, so I have a good look around to see what is there and I usually find something. If your bees are near woodland there can be some lovely fungi in the autumn.
Several years ago at Wisborough Green BKA we had an evening meeting "Wildlife in the Apiary" that was based on the photographs I took in the previous year at our teaching apiary. There were four of us who took a discipline each. It worked out well and shows how much there is to see.
Some of the buttons on the top left are linked to other websites with construction drawings of various items including nest boxes, bee posts, etc. These can be made from recycled and scrap materials, but please make sure that wood hasn't been treated. The cost can be zero as all parts can be gleaned from a number of well known sources. Hinges for doors and lids can be made from woven polypropylene, such as handles from discarded builders bags.
The hole sizes for certain types of bird boxes are quite critical. If you make it too big for the species you intend, you may get another. Wood for bird boxes is better if it is rough sawn, so the fledgelings can grip better. Don't forget to mount bird boxes out of the reach of cats. I suggest cleaning bird boxes out between October and the end of February, otherwise they may be used by the tree bumble bee (Bombus hypnorum) that has recently arrived and aggressively defends its nest.
Bee posts are very easy to make. Take a length of thickish wood, perkaps 3-4ins thick and cut one end off at an angle. On the side nearest the lowest point drill a number of holes between 4-10mm diameter angled slightly upwards. Make these as deep as you can, but if you drill right through, then simplu nail a thin piece of wood on the back. Remove the splinters from the front of the holes, otherwise they may not be used by bees.
Old corrugated iron, roofing felt, carpet tiles, car mats etc, can be put on the ground to attract reptiles. These should be away from danger of treading on them.