Recently my college purchased a small 3-D printer for students to use. While they supplied us with a heated bed for the printer, after doing my own research I knew I needed a PEI board to get the hold and smooth finish I wanted for my prints. After pricing several 3D printing suppliers online, I realized I could make my own for much cheaper. And being the poor college student I am, cheaper is always better!

If you find anything helpful in this, don't forget to vote for me in the 3D printer contest! If you have any questions, leave them below and I'll do my best to help!

Step 1: Tools and Supplies

Supplies:

Glass - equal to the size of your print bed
Sheet of PEI - equal to the size of your sheet of glass
Adhesive Transfer Tape - Like this - 1 inch width is the easiest to work with
Glass Cleaner
Lint Free Paper Towels or Cotton Rag
Masking Tape

Tools:

Glass Cutter
Scoring Tool
Scissors
Ruler - To find print bed size for your piece of glass and PEI
Paint Scraper
Exacto Knife/Razor Blades
Flat, clean work area
Cutting surface

**On your clean work area, make sure you either have a cutting mat, or are on a surface you don't mind cutting on**

Optional Tools:

Pliers
1500 grit sand paper
Isopropyl Alcohol - the higher the proof the better

Step 2: Step 1 Is Crystal Clear

I ended up getting lucky, I have a good friend that does framing. In his scrap pieces of glass I was able to find one that was almost the size and shape I needed. He was also willing cut the glass to the right dimensions for me. You'll need to cut your piece to the size and shape of your bed, making sure any necessary notches are cut into the glass.

Before starting to lay down the tape, clean your glass very well. I ended up cleaning it twice, once while holding it and the second time after I used some masking tape to stick it to my cutting mat, like shown in the photos. This keeps your glass from sliding all over the place. Once you get your glass as clean as possible DON'T TOUCH IT! The oils from your skin will keep the tape from sticking well. After you get the glass firmly stuck down and completely clean, it's time to start laying down the transfer tape.

I started at one edge of the glass laying the tape down smoothly. I left a little overhang so I had room on either end of the tape to put my fingers, that way I didn't have to fight getting the tape on cleanly. You want to leave a small gap in between each piece of tape, like a millimeter or two. If the tape overlaps it can lead to bunching under the PEI, which is not good for a smooth surface for your prints. As you lay down the tape, do your best to keep the wrinkles to a minimum. You'll want to leave the paper film that on the one side of the tape on until you get ready to lay down the PEI.

Step 3: Step 2 Is Cutting Edge

Once you have all the tape laid down, use your fingers to gently(but firmly) press the tape down, smoothing away any wrinkles or bubbles. Next using a sharp exacto knife, cut the excess tap off. I used the edge of the glass to give me a nice even edge. Even if you have to make a couple passes, you want to try and get the tape to be as even with the edge of your glass as you can.

After you get the excess cut all the way around, peel the protective layer off the tape. It's very important you remove this coating immediately before laying the PEI down. So if you have to run off to anything, leave the protective tape on! Everything sticks to this stuff, including, but not limited to, pet hair, your hair(VERY BAD for you), dust, little kid fingers, etc.. So follow removing the tape covering with Step 3 ASAP! If anything gets into the tape, sometimes you can just scrape that piece of tape off with a razor blade, if it won't come off cleanly you basically have to scrap the whole thing and start over. I speak from a couple mishaps worth of experience.

Step 4: Step 3 Is So Smooth

First off, I'm so sorry! I didn't have enough hands to get a photo of laying the PEI sheet down. But it's super simple, I promise!

If there is a protective sheet on both sides of your PEI now is when you decide which finish you want to use. Glassy side will give you smoother surface finish on your print, but will also age more quickly, require regular burnishing, and the prints don't stick as well. The matte side will last longer, but doesn't give your prints a glass-like finish, upside is prints stick better. Whichever side suits your needs better, remove the protective sheet from. It's the side that will be stuck to the transfer tape.

Pick a corner, match that corner as close as you can to the corner of your sheet of PEI. In one smooth motion, starting at that corner lay the sheet of PEI down in a rolling motion diagonally across the glass. I like to do this part relatively slowly, bowing the PEI into the tape as I go. It's more important to have the PEI completely cover the glass than it is to try and get the edges perfect on this part. In the next step we'll trim the edges so they meet up perfectly.

After you get the PEI laid down, it's important to smooth as many bubbles out as possible. I used both a paint scraper and my hands. You want to do it firmly, but gently. If you use the scraper, be careful not to dig it into the surface, you can mar your PEI board easily with the scraper.

Step 5: Step 4 Is Scored

This step requires some patience. Flip your board over and use your scoring tool on the PEI right along the edge of the glass. I had to make like 4 or 5 passes, and I alternated which direction I pulled the scoring tool as well. If your PEI is longer than your glass, you want to try and keep the the scoring line as straight as you can past the glass edge. After you get a nice scored edge, you want to move your piece to the edge of a flat surface, like shown. Then slowly, and firmly bend the PEI down from the scored line.

If after a reasonable effort it doesn't crack, go back and score your PEI a few more times and try again. You can also try flipping the whole thing over and scoring the top side as well, but that's tough because you have to try and match the score line.

Once you get the PEI to crack, repeat the above steps to get any other excess PEI trimmed off. If you have any little corner pieces, like I did, you may need a pair of pliers to help break that piece off.

Step 6: Step 5 Is Playtime

Now that you have it cut you can pull the protective coating off of the top of the PEI. If you can get your new PEI bed installed back onto the heated bed without touching it to much your basically ready to print. However, if you chose the glossy side of the PEI to be your print surface you can use a high concentrate Isopropyl Alcohol and a cotton rag to get it clean if it ends up with fingerprints all over it.

If you chose the matte side of the PEI as your print surface, no need to clean it before printing, but still try not to touch it much, as the oils from your skin will keep the prints from sticking well.

Once you add the PEI, you'll need to re-level your board. Thanks to my handsome assistant for helping me get mine back to the perfect level.

If I could put fireworks around this part I would. **Make sure you change your print head height to account for for the new height of the PEI!!** If you don't, your print nozzle could dig into your PEI and ruin it!

Step 7: Tips and Tricks

If you chose the glossy side of the PEI, you can use Isopropyl Alcohol to clean in between prints to help rejuvenate your board. Just make sure you use a lint free paper towel, or a clean cotton rag, like an old t-shirt.

If you chose the matte side of the PEI, and your board is not holding as well, you can use 1500 grit sandpaper to lightly sand the surface and restore the matte texture, follow that up by an alcohol wipe down and you're ready to print again.

PEI boards are not magic wands for printing, however, they were a worthwhile investment for me. Especially since, I built mine for basically pennies on the dollar. It cut my misprints, from things sliding around, nearly to nothing. Which, since I have to supply my own filament, saves me a lot of money. They can take some getting used to to print with. PEI tends to prefer lower print bed temps so make sure you do your own reading to verify you have the right temperature settings, both nozzle and bed, for your material.

Lastly, PEI boards can be notoriously difficult to get prints off of. It's best to pick a corner and gently work to get lifted. If you can't get a piece to pop off, let the board cool completely, the print should pop right off. If it still doesn't, pop the board into a freezer for a few hours and the print will slide right off.

**SHARP TOOLS AND PEI DO NOT MIX!!** Never use anything sharp to pry your prints off, you will irreparably damage the surface finish of your PEI. That mark will forever show up on any of your future prints.

As long as your nice to PEI, it will basically last you forever. I have made myself two boards, one glossy, one matte, and I'm able to switch them depending on what I need from each particular print.

Thanks for reading through my Instructable! If you found anything helpful or you just enjoyed it, please vote for me in the 3D printing contest. It would be so nice to have my own printer rather than having to fight for print time at college, or spend my print time fixing the printer from where other people are doing who knows what to it. I have a few big projects I want to do, like a prosthetic hand for a disabled friend, which would go much more quickly if I didn't have to wait a week between each print. And now, with summer and the labs being closed after the end of this month, it may be fall before I get access to another printer.

If you have any questions, leave them below, and I'll do my best to answer them! Again, thanks!