Intro: Engraved M&Ms
Personalized candy can make for a fun gift, party favor, or just conversation piece. While this instructable shows how to engrave custom text and images on M&Ms, the same basic technique can be used on a variety of candies. Feel free to experiment with different types of candy to see how well they take laser engraving.
I made this at TechShop www.techshop.ws
Step 1: Materials and Equipment
Vector drawing software (I used CorelDRAW)
Laser cutter (my TechShop has a Trotec Speedy 300)
3.5" x 3.5" x 1/8" acrylic sheet
Bag of M&Ms
This instructable assumes some basic familiarity with CorelDRAW and a laser cutter.
Step 2: M&M Dimensions
In order to laser engrave an M&M, we need a way to hold it reasonably flat on the bed of the laser cutter. The cross-section of an M&M has an approximate width of 0.47" and a height of 0.24". We will laser cut a series of holes in a piece of acrylic to hold the M&Ms. We want the holes to be as large as possible (to keep the M&Ms stable) but not so large that they risk falling through. A hole diameter of 0.4" seems to work pretty well. Here you can see the cross-section of the M&M compared to the hole diameter.
Step 3: Design the Acrylic Tray
Start by drawing a 0.4" diameter circle. Use the Step and Repeat function to create four more circles spaced 0.6" apart center to center on the horizontal axis. Then use the Step and Repeat function to create four more rows of circles also spaced 0.6" apart center to center on the vertical axis. Finally, draw a 3.5" x 3.5" square enclosing the matrix of circles. This will allow us to engrave 25 M&Ms at a time.
When drawing the circles and square, make sure you set the line color to red and the line width to hairline so that the laser cutter will know you mean to cut the lines rather than engrave them.
Step 4: Laser Cut the Tray
Cut out the tray on the laser cutter. I found that settings of 100% power and 0.7% speed worked well for my acrylic. Place a few M&Ms on the tray to make sure that you got all of the dimensions correct.
Acrylic works well for the tray because it is easily cleaned so there is little worry about contaminating the M&Ms.
Step 5: Make an Engraving Template
Use the design file for the tray as a starting point (make a copy of the file). Add a red 0.47" diameter circle centered on each of the existing circles. This will let you see where the perimeter of each M&M is located. Now you can place text boxes or clip art over each of the M&M locations. Try to keep away from the very edge of the M&Ms as they may not engrave as well due to the greater curvature. If you are not going to fill all of the spaces with M&Ms, you want to be careful not to damage the tray. Either delete the text/image from empty spaces, or keep the size of the engraving to the inner circle (so that the laser will only be attempting to engrave the empty hole).
I use black or grayscale for the text and images so that it is easy to configure the laser for engraving instead of cutting.
Step 6: Engrave the M&Ms
Fill the tray with M&Ms (logo side down) and place the tray on the laser cutter. I found that settings of 100% power and 60% speed worked well for the text. You will likely have to experiment a little more with the settings for any grayscale images (depending upon the relative darkeness of the images). Configure the laser cutter to engrave black and skip red (that way it won't attempt to re-cut the circles and square outline).