Lexus Key Card DIY

I’ve wanted a Lexus key card for my 2005 GS 300 S19 for ages, but they’re basically impossible to find in Europe. So I made one myself.

I used the internals from an aftermarket smart key I already had. After looking around online, I found most Toyota and Lexus aftermarket keys from AliExpress/eBay come from Lonsdor and belong to the LT20 series. My smart key is an LT20-01, and the files I’m uploading are laid out for that board shape specifically. But it could easily be modified to fit other LT20 boards or other boards with a similar layout/shape. Using an original key might work, but depending on the model they may have a different layout and would need a different design.

To get the board as thin as possible, I removed the buttons and the battery holder. I also desoldered the RFID module and reconnected it with very short, fine wires, to make it sit next to the board. For the battery I used a CR2032 with cables, which I soldered to the board.

I designed the case for the thin original emergency key just like the original, but had to make a second version, as the locks on my 2005 GS only accept double-sided keys. I think Lexus used one-sided keys from 2007 onwards. The second version keeps the standard double-sided TOY40? keyblade inside the case, which I removed from its housing by pushing out the pin in the handle.

To make it perfectly fit in my Lockcard Wallet, I mostly stuck to standard credit card measurements (85 × 53.8 mm), but also made a version with the smaller size of the original (79 × 53 mm). It is 4.7 mm thick in total, so roughly 1.6 mm thicker than the original.

I secured the electronics as well as the lid with thin double-sided tape. The lid can be removed carefully with a fingernail.

I suggest printing at >50% infill with a 0.1 mm first layer. Depending on your printer’s accuracy, you may need to tweak your slicer a bit to make the clips fit.

My final prints were done on a Bambu Lab H2D with PETG-CF.

There are 4 models in total:

LexusKeyCard: Original-size emergency key case — 79 × 53 mm
LexusKeyCard_Key_Inside: Original-size standard key inside — 79 × 53 mm

LexusKeyCard_Bigger: Credit-card sized emergency key case — 85 × 53.8 mm
LexusKeyCard_Key_Inside_Bigger: Credit-card sized standard key inside — 85 × 53.8 mm

FYI: I didn't test print the smaller versions, but they should be fine.

I’d be happy if you share your makes or remixes! Please remember to credit and link back to this project when you do.

Note: Lexus is a registered trademark of Toyota Motor Corporation. This is an unofficial fan project and not affiliated with or endorsed by Toyota/Lexus. Modifying key electronics can affect immobilizer behavior and vehicle security — use at your own risk and test thoroughly before relying on a self-made key.