This is a Balisong/Butterfly pen that is fully functional and that can be used as many times as you want, you just need to change the ink cartridge when it is empty. It's about the same size as a regular pen and the balisong handles are smaller so the pen can be used even if it is folded.
If you like it please vote for me in the 123D Design Challenge.
Autodesk 123D Design
Ink Cartridges for Pens ( If you want to, you can use Gel Ink refills just change the design of the pen so it can fit the refill)
A 3D Printer
If you don't understand something please ask me. I will leave a link to download the one I made if you need reference or some help.
Step 1: First Step: the Handles
Open 123D Design and Create a new project. First of all, change Units from mm to cm in the bottom right corner. Now go to sketch and create a new rectangle of 1.4 cm width and 12.5 cm height. Now you can round the edges using the Spline tool, just click on the existing sketch to edit it. I made a perfect semicircle in the bottom using the 2 point arc and a spline in the top. Delete what is left of the rectangle.
Now go to Construct, Extrude and click on the shape we made. Type 1.4 cm in the little box that have just appeared. Now go to the Right view and make a rectangle of 1 cm x 16 cm on the side of the shape we made a moment ago. The rectangle should look wider than the shape. Now go to the move tool ( the one that is to the right of the arrows) and click on the rectangle and move it so you have 0.2 cm between the end of the rectangle and the shape ( look the pictures) . I used a spline as a ruler so I can move the rectangle to the position indicated above, 2 mm below the top of the shape, just make a spline of 0.2 cm and move it to the top of the shape. Now extrude the rectangle and in the little box put -1.2 cm so it will make a hole in the shape.
Now change to top view and horizontally make a spline of 0.7 cm and where it ends make another spline that goes straight to the top. Now vertically make another spline of 1 cm and where it ends make another spline horizontally so it will touch the other one. In the point where the splines intersect you're going to make a circle of 0.5 cm. Now extrude the circle and type in -1.6 cm. This is where the bolt is going to come through. Now you have finish the handle, if you want you can add holes like me to make it more detailed. When you finish detailing the handle just copy and paste the shape ( ctrl c + ctrl v //// cmd c + cmd v) and now you have the 2 handles.
Step 2: Step 2: the Pen
Now that you have made the handles you need to make the pen. Create a circle with a diameter of 0.8 cm. Now extrude the circle and type in the box 12.3. Now go to the bottom view where is the sketch of the circle. Click on the sketch and again extrude it but now type in - 1cm. Before you hit Enter you have to adjust the angle. Click on the little white circle and type in - 6 cm. Now you should have a cone but with the end trimmed. Go to the bottom view and make another circle of 0.5 cm in the center of the cone. Now extrude it and type in the box 12.7. Now you should have a big hole in the cylinder. You have finished the pen, now let's make the thing that will put everything together.
Step 3: Step 3 : the Thing That Puts Everything Together.
Now we are going to make the part that will join every piece we have built. First create a rectangle of 2.6 width and 2.5 height. Use the spline tool to make lines to cut the edges. Now use the Trim tool located in Sketch and click on the lines that form the edges so the tool will eliminate them. Now use the spline tool to make round edges around the rectangle, you just have to click and hold in one point and go to the other one and then release. Now that you have a rectangle with round edges, you're going to take the spline tool again and horizontally make one line of 0.5 cm and another one of 0.6 vertically. Now make a circle of 0.5 cm where the lines you just made intersect. Make the exact same thing in the other side of the rectangle. Then select the rectangle without the circles and extrude it. Type in 0.9 cm and you should have the rectangle with the 2 holes. Now take the pen and with the move tool place it in the middle of the rectangle and then push it towards the rectangle so the pen will be inside the rectangle. Try to place the end of the pen almost touching the end of the rectangle. Now select them both and group them ( go to the circle/triangle/square icon and select Group).
Step 4: Step 4: Assemble
Now you just have to print the parts and with the 2 bolts and nuts put it together. The bolts go into the 0.5 cm holes we made. The bolts' size can change according to the design you want to make. Also put an ink cartridge of the appropriate size in the hole of the pen, I just buy regular pens and took out the cartridges. You can change the cartridge when it is empty. Now you're done! Have fun with the Balisong pen. Please Vote for my in the 123D Design Challenge. Thank you!
The 3d model I made is here if you just want to print it or you need to take a look at it :
123D project (123dx) : http://www.mediafire.com/download/ro1fxd1a2a75b3e/Balisong_Pen.123dx