So you have spent a lot of money on your diy quadcopter(or any multirotor) and refuse to give any more, but you still need a propeller balancer. Balanced propeller is very if not the most important thing for multirotors.
Guess what, you can make your own, from old computer components.
If you happend to work in ICT company, there is always a lot of that stuff around. Besides broken hardware, some tools may also come handy. Let's begin with stuff you are going to need.
Step 1: First Things First
If you are lazy and don't care about 20 bucks, go and buy propeler balancer. Go for a booze right away.
Step 2: Stuff and Tools
1. Piece of wood,
2. Set of screw thingies,
3. Drilling machine,
5. Angle grinder,
6. Broken DVD writter,
7. 4x Hard disc drive,
8. Rack server,
10. Ruler and
12. 2-8x Pen
Step 3: Disassembling Hard Disk Drive - Harvest Magnets
Disassamble hard disk drive with appropriate screwdriver. Make sure you have made backup before. If you are stuck with some plastic hooks, take hammer and brake them. Repeat as many times necessary. Don't worry about hammer and you can't overdoit smashing hard drive. Now if magnet is free to take out, take another hard disk and repeat this step 3 more times.
Now you should have 4 magnets. If you have less, you don't know how to count or you dissasambled some SSD or whatever.
Step 4: Disassembling Hard Disk Drive - Harvest Metal Axle
Use screwdriver to unscrew all screws. Now, it won't allow you to open it just like that. Help yourself with hammer, convince him. Eventualy all vital electronic parts will move away in several dozen pieces. Take out shorter axle and throw away smashed DVD writer into garbage(recycle!). Or you can intall into colleagues PC. Either way is ok.
Step 5: Rack Server - Harvest Hdd Case
Download manual for your rack server and find a way which one of 2 possible plastic handles enables taking out hdd case. After that, unscrew 4 screws or 5 or 6, depends on the case. All you need from this are two metal side thingies. Rest of the case you can put back into rack server. Then you can practice hammering on server.
Step 6: Drilling Time
Find somewhere in the workshop 3mm bore. It will fit with almost any screw from bowl of screws.
Most certanly you will find 2mm and 4mm. If that is the case, call your boss and tell him that workshop doesn't have 3mm bore. Then go to the hardware store and buy it. Next day you will notice few evil eyes in the office.
Make two holes on each side of wooden piece with cool black stripe. Make sure those wholes actualy fit in metal thingies from hdd case. It is recommended to use angle ruler. If you have sharp eyes and good normal ruler, it will be fine. I didn't have angle ruler.
So now you have 2 holes. Take 4 screws from bowl of screws. Screw them. Screw them good.
If everything is screwed good, you will have 80% of the final product.
Step 7: Steel Some Pens
Steal 3-4 pens from office. Don't use your pen, it's more fun to steal from colleagues. Next day they will be surprised. Blame the janitor the cleptoman.
So now you are full of adrenalin because you stole 3-4 pens. Unscrew(without screwdriver) pen tip thingie. Use the adrenalin from stealing and take sandpaper and sandpaper them. Also sandpaper them goood. The point is, we need get enough big whole for pen tip thingie go through metal axle from dvd writer. If you overdo it, go and stil some more pens. Enjoy the extra adrenalin. Feels good? :).
I hope the office had enough pens for you to make 2 sandpapered pen tips thingies.
Step 8: Sharpening Metal Axle
Roll your sleeves and take angle grinder. Each second you are becoming a more manly man. Beard is growing 1mm/hour. Grind metal axel to get sharp edges. Grind it until is about 5mm shorter then U profile made from piece of wood and 2 metal thingies. If you wish, you can use handsaw for shortening first, then grinding to get sharp edges. Either way is ok. Depends how much beard do you want to grow that day.
Now you are 95% finished.
Step 9: Finalising
Rest 5% is asembling magnets on metal thingies. Put pen pins into metal axel with propeler between. Friction will help to stick 3 things together.
Congratulations you are finished. 20 bucks stays in pocket, speend it on booze.
May you multitorors fly without any vibrations and the force be with them.
p.s. Stolen pens problem have few solutions. Burn them! Blame on janitor the cleptoman. Take a vacation 2-3 days.