My dad (a joiner all his life) has been keeping himself entertained during the lock down by making bird boxes for friends and family. So far, he's made both all-purpose, general boxes and robin-specific boxes, but he's got other types on order, including tree creeper and owl (when a supply of wood turns up).
They are just £5 each (though the owl boxes will cost more). Check the photos and message me if you're interested.
Also, if anyone has got any spare wood that would be suitable for him to use, get in touch!