Your Crazyflie is an awesome investment and it might need some extra protection while you get the hang of flying it. This instructable will show you how to fashion a lightweight and effective set of prop guards for it. With a little creativity, you could do this with just about any micro quad. All you need is some velcro wrap, aluminum wire and electrical tape.
Step 1: A/B Velcro
Start by cutting appropriate lengths of velcro from your a/b roll. A/B velcro is not sticky. It has two different velcro sides, so it can stick to itself. I used 1" cuts for the leg wraps and 2.5" wrap for the body. You'll want to get a 3/4" width roll so you can still see the LEDs after wrapping it up. The cool thing is velcro tape is super lightweight and re-usable. Plus, its velcro so you can attach other velcro items to the quad if you want to later.
Step 2: Aluminium Hoops
Jonny Ive aint got nothing on your aluminum fabrication skills. Get your googles on and cut four lengths of thin gauge aluminum wire. I used around 7" per hoop. Use your pliers to fold the ends so they are not sharp. Fashion the hoops into clover shapes so that they will fit nicely in the quad corners.
Step 3: Electrical Tape
Use some electrical tape to secure the hoops together end to end. You should end up with a four-leaf clover as in the pictures. This will keep your electrical components safe too. After all the hoops are secured. Put the whole thing on the floor and press it flat with a book.
Step 4: Attach the Hoops
Attach each leg to each end of the clover structure. Open the velcro tape and tuck the ends neatly under each leg and close the velcro on itself.
Step 5: Finishing Up
Tighten up the velcro on each leg and pull the hoops out to the end of the legs. The end result should look like this. Finally, add a little flair with a pin on the front. Use whatever! Open the pin back and push the wire into the velcro. Don't prick yourself. You are now ready to fly! The hoops might get deformed after a crash, but it should be pretty easy to bend them back in place. Safety first! Enjoy.