February 18, 2026
Description
The goal behind this project is to have a cheap and accessible physical signal blocker for everyone that is:
Simple to construct,
Robust enough to be used multiple times and thrown in a bag or backpack
Quick and easy to retrieve the device or seal the device inside when needed
Most importantly- Able to continuously block Cell service, Bluetooth, Location Services, etc.
If you have a device that needs to stop broadcasting and receiving signals or would like to hide your location data for a period of time I hope that this print can give you an extra layer of certainty.
I recommend printing in the default orientation of the files, no supports will be needed but the tray might be tight if your printer has poor bridging. I printed in PLA+ but PETG should also be great.
I would like to say that I am not an expert on this topic, but I did do testing to verify that the Foiled cage can block the following for at least 30 minutes continuously when assembled as shown below and completely closed.
Bluetooth connections
Cellular service
Google Location Services
Fully hidden from Find My Device
To be sure that your Foiled cage is actually able to block signals I highly recommend testing it after construction.
place a phone in tray and seal the Foiled cage by folding/rolling as shown below
try connecting with a paired a Bluetooth device
try calling the phone
try to find the device on maps or with location services
If supported try to locate the device with a "Find my device" service
wait 30 minutes and check #2-5 again.
If the phone has not been spotted by any service in the elapsed 30 minutes of testing then the Foiled cage should be working.
To avoid wasting battery, don't forget to turn on airplane mode or shut off the device before real world use!!
If you need to block signals immediately and don't have time for the print to complete, I've found that wrapping a device with a plastic bag of any variety (for isolation) and then wrapping it at least 5 times around with foil will also block signals well, however this is more prone to failure, slower to seal or unseal the device for access, and not as easily reused.
The cage is currently sized for most Standard (160mm x 80mm x 15mm) and XL (190mm x 100mm x 20mm - untested) sized phones with allowances for cases.
The STEP files are included for more precise parametric sizing if desired, I suggest fudging a few mm of leeway to make it easier to get the device in or out of the tray and not going much above the dimensions of the XL cage (100mm x 190mm x 20mm)
These are the dimensions to edit for resizing:
Once both components are printed it's time to prep the foil. I recommend getting sheets that will wrap around the cage exactly twice and layering at least two sheets. For the 160mm cage I found this sheet length to be 430mm
For a rough approximation of how long to cut foil sheets try this quick formula:
(Width + height) * 4.3
Tie a string or paracord to the loop on the tray component so the tray can be pulled out easily later and insert it into the cage component
Lay the aluminum foil flat and place the cage on the foil as shown. to ensure proper fitment pull the tray out until it almost falls out of the cage then align the edge of the foil with the midpoint of the tray.
Pull the end of the foil halfway over the cage, I recommend securing it loosely with tape for further alignment
Roll the cage over 180 degrees to make sure the outside edges of the foil will stay aligned when wrapping
Unroll and secure with a second piece of tape once the edges are properly aligned
Roll up all the way and secure with tape. repeat steps 1-5 at least one more time or blocking may be very unreliable (try to wrap the foil fully around the cage at least 4 times, 6 or more times to be extra sure.)
Collapse the foil on the closed end of the cage print
Fold over the foil on the closed side by folding it onto itself once or twice then folding once over the bottom portion of the cage.
Smooth out the edges of the folded portion
Flip it around and make sure the loose edges of the foil is tidy over the tray
Tape over the edges on the top and bottom to strengthen and improve re-usability, don't tape the sides as it will make it harder to roll up
Slide the device into the tray
Push the tray fully closed and tuck the string in the pocket.
Fold/roll up the open end of the foil and test you blocker!
License:
Creative Commons — Attribution — Noncommercial — Share Alike
THEscurge
