These are two designs for Arduino carrier boards that you can mount an Arduino, breadboard, and battery holder(s) of your choice to. These are great if you want to run your Arduino project without being tethered to a wall or a PC and are great for Arduino classes, as you don't have to have a PC or wall wart for each participant.
The smaller version has space for a 400 point breadboard and your choice of either a 9-volt or AA/AAA battery pack. The larger version with space for a 830 point with both a 9-volt and AA/AAA battery pack (great for applications where you want to run servos or other devices off a separate power supply from you Arduino).
Cut the black lines and etch the red lines in 3mm acrylic.
9V batteries and 4-8 cell AA and AAA battery packs can be held in place with 1/2" wide Velcro cable management straps, or the SparkFun 9V battery holder in the case of 9V packs (attaches with three 3/8" long #2
9V to barrel jack adapters (http://www.sparkfun.com/products/9518) can be used with 9V battery packs as well as snap connector based battery holders:
I like 8 cell AA holders as they provide plenty of voltage for even high drop out linear regulators when using rechargeable cells, and should power your typical Arduino project for a loooooong time.
I attached my Arduino with 3 M3x16 bolts with 1/4" nylon spaces. The Arduino mount is updated with a fourth mounting hole for newer model Arduinos, which I needed because I wasn't able to use one of the 3 original mounting holes Arduino because of the added ICP header on the UNO.
If you don't have access to a laser cutter, you can grab a kit of these boards or just the laser cut plates from my store here: