Introduction: Sacrificial Phone Case Bumpers

About: i have spent my life finding alternative ways to get every task done in spite many challenges. most of my projects are as we call how we do things Fabrecobled (to make (fabricate) something from whatever layin…

Farming needs tough tools! My last phone died when it got body slammed when it fell out of my pocket while whipping a pulse wire (freeing from a snag). It was in a "tough" case well expensive anyway. This is when I observed that phone cases are designed to handle minor impact loads. And thought that if cases were built a bit like helmets might be better. So I built a few different designs for my phone settling on a design that did minimized 2 impacts on the same corner before I got a new corner printed to replace the broken one. My case is designed to be clipped onto my shirt pocket to help me video projects for making YouTube (check out my videos) videos and Instructables.

That said lets make some basic sacrificial bumpers.

I need to upload many files to thingiverse (I am lazy when it comes to the not making part of our community. But I can change if I have to I guess?) The appropriate links will be added as I get files to thingiverse.


  1. finished and printed corner.
  2. supplies.
  3. corner that probably saved my phone and new corner set.
  4. corners on my phone case.

This has worked for my phone, but I can not insure the corners (by my design or yours) will work on your phone. You are responsible for the risks you take.


  • Cell phone
  • Cheep case (optional)
  • Paper and pen
  • cutting tool
  • Measuring device (I used a calipers)
  • Computer (with a way to make a 3D printable file) I use fusion 360 and this would be a great project to learn on.
  • Access to a 3D printer (if using fdm do tolerance tests, or design with wider tolerances)
  • Mounting tape
  • Willingness to fail (because that's how we learn most)

Step 1: Measure the Phone and Design


  1. make a rough drawing of the phone
  2. measure the distances to all buttons, microphones, cameras and etc
  3. document placement on the drawing


For basic corners we are only designing one that fits on all the corners.

  1. To do this you want to identify how deep the corner needs to be from front to back of the phone and the shortest distance from a edge or corner to one of the objects listed in 2. above.
  2. Now add the thickness of the mounting tape to this number. you may also want to add a little to the depth of the corner to provide a screen offset when phone is set screen down. (see green pen on the drawing)
  3. now draw a general shape of the corner you want with the dimensions you determined. (see drawing)
  4. now recreate the general shape and fine tune your design in the software of your choice. I used Fusion 360 see my video on how, Tinkercad is good to. (especially if your not familiar with CAD programs)

Step 2: Print and Assemble


  1. Import the STL file of your corner to your slicer program. You should put at least 4 corners on your build plate (I put 6 on and broke 2 removing them ending up with the right amount but will need to print more when one breaks.)
  2. Print the parts remember print more then you need.
  3. Finish parts as needed. (scratched the surface to help tape to stick see picture 5)


  1. dry fit the corners to make sure they won't interfere with the phones function. (see picture 4)
  2. SLA prints don't stick well to a number of adhesives without help. (scratching the surface helps see picture 5)
  3. apply mounting tape to appropriate locations on phone or corners. (see picture 8) (a couple one handed tape cutting techniques pictures 6&7 (should I make a one handed tape management Instructable?))
  4. arrange corners to make sure you put the tape where you wanted it. (see picture 9 (not taping the top and bottom of the phone because the body is curved reducing contact area (could design corners to fit curve if you felt like it)
  5. dry fit again with mounting tape applied. (see picture 10)
  6. peal tape backing and apply corners to the phone. (see picture 12) (picture 11 is to show how a snot rag can be used to protect the phone screen from the work surface when applying pressure)
  7. just for fun add color to the design (if you want) (see picture 12)

ALL Finished

Step 3: Nop (I Said Somthing About Sertain Printed Parts and Adhesaves (what Was It?????))

Some printed materials don't get along well with adhesives.

One corner decided it didn't want to stick so hot glue between mounting tape and well scratched corner did the job. (see picture 1) (moments later the other three corners got jealous and mutinied. Hot glue for one and all!)

So trouble shooting time

  1. Is there texture for the adhesive to bond to? if not scratch up the surface with a suitable tool.
  2. Still no good? Try a different adhesive between mounting tape and corner. (Probably don't want to stick add adhesive directly to the phone (mounting tape has stuck well to all the phones I have used it on and removes without much trouble.)
  3. Is there good contact area? If not redesign the part to better fit the phone. (see picture 2 of the corners on my phone.)

Good luck. Keep Making.

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