If you happen to own or have access to a 3D printer, the following addons might be of interest to you.

• Bitcraze Crazyflie frame by VGer: A protective frame that attaches to the motor mounts of your Crazyflie and includes some safety loops to protect the propellers. Also allows to mount the battery beneath the Crazyflie thus lowering the center of gravity. Weighs around 3 grams.
• Bitcraze Crazyflie washer by VGer: A small washer to use to protect your motors from depressed-bearing-syndrome. Print 4 of those.
• Crazyradio housing by foosel: A small case to house your Crazyradio so you don't have to handle the blank PCB all the time
• Crazyflie frame by VGer: Updated version of VGer's frame (v1.7)
• Crazyflie re-inforcement for broken arm fix by petr: Frame that reinforces the existing arms and allows broken arms to be used. Currently a bit on the heavy side.