Some research has suggested a relationship between exposure to EMF (electromagnetic fields) and the development of cancer.  Without conclusive evidence to prove or disprove causality, caution is worthwhile.
If you are concerned with the risk and want to protect yourself from high intensity EMFs from holding a cell phone next to your brain, one option is to put the cellphone in your pocket in front of a PLASTIC VACUUM-FORMED CASE with FELT SPACER to hold the cellphone antenna away from your skin.  The phone can then be used with Bluetooth, a headset, or put in speakerphone mode.  I have found that this also improves both phone and GPS reception.

I made this device at TechShop ( and my procedure is listed below.

Step 1: 1. Materials List

Clear PETG plastic sheet or white polystyrene available from TechShop in-house store - size should be large enough to fit into the smallest plastic holding frame of the vacuum former

3 x 4 x ¾ inch smooth wooden block (MDF works well)  available from TechShop wood scrap bin

3 inch x 4 inch, 5/16 inch thick felt to use as a spacer

Contact cement to hold the felt in the case

Step 2: 2. Procedure

Cut the piece of smooth wood to the size you want to fit into your pocket. I cut to a size of about 2 7/8 X 4 X ¾ inch using the band saw.

Step 3: Sander

Use the sander to sand the edges so they slant inward toward the top surface. This
helps the wood come loose from the vacuum formed plastic. I also rounded the vertical edges.

Step 4: Vacuum Former

Next, put the wood on the vacuum former grid and choose a plastic sheet frame size that will hold your plastic. I lowered the wood block with the lowering lever and clamped the plastic sheet down and set the temperature of the heaters to 50%, which worked well for the PETG plastic I used.

Step 5: Place Plastic Sheet on Vacuum Former

I let the heaters warm up for 15 minutes and then rolled the heaters into position over the plastic.

Step 6: After 90 Seconds

After 90 seconds roll the heater back out of the way.

Lift the grid with the wooden block all the way up past the sagging plastic surface and push the button to turn on the vacuum.  I waited 15 seconds before turning the vacuum off.  This picture above shows the start of the vacuum forming.  I used white polystyrene and clear PETG.  I like the clear better.

Step 7: Cool the Vacuum Formed Plastic

Cool the plastic sheet with an air nozzle until it is just warm to the touch and press the release button to pressurize the plastic to help release the wooden block.

Unclamp and raise the plastic sheet frame and remove the plastic. The wooden block should come out easily.

Remove the plastic sheet and take it back to the band saw to cut the case shape away from the plastic sheet and cut one of the shorter ends off at the same time.  This allows the cellphone to slide in from the top of your pocket.

Smooth the edges, then cut and glue the felt to fit into the case.

I placed my cellphone into the case with the touchscreen against the soft felt and then put both into my shirt pocket. It fit great and now the cellphone antenna was spaced further from my body. My pacemaker skipped a beat, but I felt good to extend my lifespan by 30 years (read my next book if I ever write it).

Instructables Design Competition

Participated in the
Instructables Design Competition