It's a head-spinning 10-Fer! Ten fans for ten bucks! These cute little 2" square 50mm muffin fans by Runda operate from 6-18VDC, and they’re rated at 18 Volts. They’re pretty gusty at 12VDC and run strong off a single 9-Volt battery. Each fan is 10.5mm and has (4) mounting holes in the corners. These are take-outs from unused equipment, and super clean. Great for group projects. Think: Scouts, classrooms.

This little black plastic fan and frame measures 2” square x 7/8” thick, and is a 12VDC 0.15 mA brushless model EFB0512HA. Has an air flow of 11.40cfm, and spins at 5500rpm. Able to operate from -10 to 70 degrees Celsius. Has a pair of 6” long red/black leads with a quick-disconnect.

Muffin fans, pay attention. You pick the "nice" 110 VAC 21W fan from Thermocool, measuring 4-3/4" square x 1-1/2" thick with an unwired offset two-pin power connector, rated for 82-95 cfm and spinning at approx 2600 rpm, with five blades and 3/16" mounting holes at the corners (Mfr part # G12038HA1ST); or the "beastly" 110VAC 36W muffin fan from the same mfr, which blows up to 198 cfm at 2900 rpm and measures 6-3/4" x 6" tall x 2" thick with (2) power terminals on a removable shroud, 5 blades, 5/32" mounting holes on the corners plus a ground lug. Both UL.

This 12VDC low-pressure, piston-driven, diaphragm air pump has a 7/32" inlet. This bad boy is rated between 6-12 VDC with 12 VDC being nominal voltage , draws 1.3 amps at 12 VDC.  Overall size is  4" x 1-5/8" x 3" with solder tabs but some may have 10" leads. Shaft has a 1/2" dia cam to drive the piston. Motor is Mabuchi RK-555PH.

This little L-shaped low-pressure piston-and-diaphragm air pump has a 7/32" OD inlet and an 11/32” OD x 9/32” ID outlet, and is attached to a Mabuchi RK-555PH 12VDC motor that draws 100mA no load, stalls at 4.3A, and spins approx 3500 RPM. Measures 4" x 1-5/8" x 3" with 2” leads.

Of course you’re not, but you might like squirrel-cage fans like we do. If so, this take-out, cream-colored ABS plastic squirrel-cage blade is for you. Originally from portable AC units, they measure 6-3/4" dia x 3-3/8" across with a flattened 5/16" ID bore and a 3/4" shaft that extends 7/8” into the cage. Could be re-rigged for a gerbil wheel. Made in USA.