Introduction: Business Gun-Card - Rubber Band Gun

About: I'm a mechanical engineer in the Eindhoven region. In my spare time I like to make random stuff, both usefull and especially useless.

Here it is, the business shooter card for all backyard inventors. But what is wrong with a normal business card you ask?

What if you're about to have a job interview and the persons next to you have one of clide's business cards? Using their heavy artillery, both the cardapult and trebucard, they try to shoot you right out of the field. But wait, you have a big advantage over your opponents, you're agile. With your two shot gun-card you move through the field. You got them both before they even know where you are. The battle was yours, now it's time to win the war. Time to reload and enter the job interview.

Alert: don't use this war-equipment the wrong way when the final battle is at hand, the war isn't won that way.

Step 1: Materials:


  • Pen and paper
  • Excel
  • CAD software


  • 3D printer
  • Three rubber bands - 1 for the mechanism, 2 to shoot
  • Superglue
  • Sand paper / small file

Step 2: Design

It all started out as an idea when I was at a mini maker faire a couple of years ago. There was a guy showing all his homemade rubber band guns. I saw the business cards of Clide just before that when searching for business cards here on Instructables. So I started talking to the guy and an idea was borne in my head.

I designed the first three versions using Microsoft Excel (see image). Turned all cells in squares and started 'drawing' my design. The design was a three layered double shot revolver the size of a credit card. A part of the card, which should contain my info, was removable. I build the first prototype, but the mechanism didn't work and the trigger was way too flimsy. Proto 2 solved the trigger, but only after that iteration I realized the mechanism didn't work. So then came the third iteration, but before I made this one, I changed the idea a bit.

In the end the business card was a combination of the last Excel-design and Jimmy Diresta's Key Card. The gun is constructed of three printed layers glued together. It took me another 3 3D design iterations to get to the final version of the card. The two outer layers have a debossed area. By transferring that debossing using pencil, one can get your contact info.

Step 3: Print and Build Your Card

Before you print your card, first you need to add your contact information to the design. You can use whatever CAD-software you like. Add the info en deboss it 0.2mm downwards. Only add information to the outer layers, the middle layer won't be visible. A version with the Instructables logo is uploaded as well.

Once you have added your contact info, export the 3d files to you favorite slicer software. The card is designed to be printed in 0.2mm layers. A gap of 0.2mm is left open between the sliding parts. If your printer is not accurate enough, consider printing the parts 'out of place'. You can afterwards tweak the fit with a file or sandpaper.

After printing it is time to glue the parts together. The first glue image shows which parts need to be glued first. After gluing you can remove some of the excess glue. I also flattened the prints with a file to remove any sticking out filament (due to for example retraction). Now glue on the other side. If you did it correct, you still have 4 small pieces left. Make sure the gun is in it's 'loaded' position, you are then able to glue the 4 pieces to the middle layer.

The gun should now be able to work. But to make the business card part work optimal I would advise to sand the outer layers a bit smooth.

Only one task ahead before we can go and shoot our card, to add a rubber band in the 'center' of the card as can be seen in the image. This rubber band brings the card in shooting position.You should now have a working gun-card.

Step 4: Play

Alright, time to get to the fun part. Using your gun-card.

Add two rubber bands as can be seen in the image. Ready?? .. .. .. Fire!! Great shot, you hit the trash can. Fire!! Another great hit. Your future employer seems enthusiastic. Quickly grad a piece of paper and pencil. Put the paper on top of the gun-card and start 'scratching' with the pencil. The debossed information should now transfer to the paper. Provide the employer with the paper and thank him for the interview. The battle again seems to be in your favor, but only time will tell whether the war is won.

Rubber Band Speed Challenge

Second Prize in the
Rubber Band Speed Challenge