The first one is a small omni microphone named "XLR omni" seen on the moosapotamus website and inspired by circuits found on Dave's Latchaw's website mp3forkidz.com. It is based on the Panasonic WM61a omni electret condensator capsule, a loved capsule among the Diyers community, and used in many projects. The good things about this mic are its low cost (you can find the capsule for 2 ~3 Euros), small size, simplicity, and relatively good sound quality. One of the main advantage is that it is self-contained in a XLR connector (for this i recommend the "Amphenol AX3M" after having tried some neutrik's too), making the construction pretty simple and quite cheap, and allowing to use them in some tight space configuration. We made also a version with a remote capsule attached on a cable, aimed for a use as an Instrument clip microphone. Sonicaly it is pretty decent, okay it might be a bit on the noisy side, but we used them as ambiance microphones with quite nice results !
The second build is the "Alice" microphone made by Scott Helmke and found on his interesting website: http://scotthelmke.com. It is again an electret small diaphragm condenser microphone but this time with a cardioid polar pattern, based on the Transound TSB-165A (can be found at www.jlielectronics.com/ for 9 dollars plus shipping and taxes) a more professional capsule as said by Scott Helmke, which require a bit more complicated circuitry.
The building is also more complicated as you have to find a body to fit in this bigger capsule, the circuitry and a XLR connector, which requires some metal work and building skills, but nothing insurmountable. We choosed to build it, as Scott did, with copper pipes, as it is an easy metal to work with (soft) and you can find it in almost every hardware shop for a reasonable price. There is although some difficulties, for example we couldn't find a fitting round XLRs connector at an affordable price. The trick was to modify a panel mount XLR connector (like the Neutrick NC-3-MP or equivalents) and cut it to a round shape. Using a 22 mm copper pipe the XLR connector passes almost perfectly in the tube. Unfortunately a 22mm (~20mm inner diameter) pipe is a bit too small for the capsule when you want to add the grille around it. For this purpose we used a 22mm to 28mm pipe adapter allowing more space for the capsule and giving some "character" to the design. The electronic schematic is also not that hard and the parts quite easy to source (we got everything from www.banzaimusic.com). Unlike Scott, we also made a real PCB using the toner transfer technic, giving easily nice clean results at a small expense. We builded four of these small condensers, and are quite impatient to use them on coming productions. We cannot really talk yet about their sonic qualities, but would be pleased to share our experience in the next months.
Don't hesitate to write us if you need some advice and infos or sharing experience with DIY microphones.