[pgkevet]

[member=2128]Womble[/member] - And usually the concept is a light-bulb moment that once shown is easily copied and knocked off cheaper with economies of scale and china..
There is (or was while I was working) a UK company selling way better designed iv giving set components - kink free tubing and connectors that can freely twist and devices to help prevent pull-out and better pumps that costs 3x as much but the accumulated cost of using them on a patient meant we 'saved' them for really difficult patients and kept battling on with conventional stuff on the rest purely to keep costs down to the client or risk being labelled as a high end overpriced rip-off clinic...

[Buttermilk]

My neighbour designed and built just such a bob hole into his hen house about 15 years ago.  They have given up keeping hens now though as birds of prey picked them off as they pecked around his orchard.

Did it work or were there problems, can you remember?

He had it in place for nearly 3 years so I reckon it worked.  It did not stop his banties from perching in trees though, or the silly orpingtons from going broody under the hydrangeas.  It did keep the pheasants out which was his main intention.