CRAS Instructor Chris Bailey has a great site called Creativity To Spare that deals with a lot of very cool audio and video techniques, tips and tricks. His Podcast #5 above teaches you how to make your own condenser mic for $20.
Parts list and related info:
The Mic Element
WM-61a Panasonic – digikey part #P9925-ND $1.86
10uF Metalized Poly Capacitor – digikey part #EF2106-ND $4.48
2.2k ohm metal film Resistor – digikey part #2.21KXBK-ND – 5 for $.49
1000 pF ceramic Disc Capacitor – digikey part #1457PH-ND – 10 for $1.97
9 volt battery holder/clip with leads – digikey part #BH9V-W-ND $.86
A possible supplier for XLR connectors
Full Compass Parts will be cheaper in bulk. This is as high as they could be.
NC3MDL-1 XLR 3pin Male Panel Connector $2.70
NC3FDL-1 XLR Female Panel Conector $2.82
This is the old style I used for the mic itself. It’s a bit difficult to put the mic element in the end.
NC3MX Male XLR Connector $2.52
This part will be more money, but could make assembly way easier.
NC3MRC 3pin XLR Male Right Angle $7.42
Then you need point to point wire for inside the box.
Thin very flexible wire for wiring to the mic itself.
Solder and irons. Heat shrink tubing can be useful.
Junction boxes and covers.
Screws to mount the panel XLR connectors.
Other Misc; A metal file – The knock-outs on the junction boxes are just a tad small for the Neutrik XLR panel connectors, so the hole on the ends will have to be enlarged. I have tried everything and a simple metal file (round) is the answer.
Drill Bits to make the hole for the screws for the panel connectors. These have to be able to drill into really hard metal (ie. buy a FEW).
One tube of 5 min epoxy will do for many Mics.
A 9 volt battery.
Something to test it with. (ie a mixer and headphones, and mic cables)
Hardest part of the whole thing is soldering the back of the mic, it is small and if you leave your iron on it for to long it will fry the mic electronics.
Suggestion buy some extra mic elements – they are cheap.