Recently I took my recording rig with me on a trip to visit my wife's hometown. My father-in-law runs a small sign printing operation out of a converted barn and I thought I could spend some time in the shop recording the various machines. He has been in the printing business for almost 40 years and has some great devices from the pre digital days. Although I got some great stuff from the various kinds of printing press and machines my favourite sound discovery was the drying racks.
As you can see the rack consists of 25 levels of metal trays, each level is spring loaded so it can be lifted upwards to get at the tray beneath it. It works almost like a giant metal book. They are designed so that you can air dry multiple prints at the same time, all stacked on top of each other. The racks are not very loud when listened to normally, but if you place a contact microphone on the rack and listen through it - a whole new world of sound appears.
I have not used any processing on this at all, all the reverb you can hear is the actual rack resonating, and man can it resonate a long time. Just walking near the racks set them off on long slow metallic rings that seemed to last forever.
In this first sample I am simply raising and lowering the 15 racks above the one the contact mic is resting on. It basically becomes a horror film sound track.
The drying rack was originally a stack of 50 individual racks but in order to get it to the second floor of the barn it had to be split into two units of 25 racks each. The second unit sounded similar but had a lot more presence from the actual springs attached to each rack. You can hear the springs "popping" quite a bit in this recording of the second unit.
Another great sound I stumbled upon was simply lightly kicking the bottom of the rack to get this great low metal hit. You can hear a couple at the begining of this clip followed by more grinds of the trays being lowered and raised.