OK, let's assume that 50 mA is the correct current. There is a nice little IC driver that will put out a constant 25 mA into your LED, parallel two drivers and the total LED current will be 50 mA. Cost is $0.38 each. Of course you can parallel more, each one adds another 25 mA to the output current.
The paralled driver can drive LEDs in series as long as the battery voltage (nominal 12V) minus the total voltage of the LED string is more than 5V. The "headroom" required for the driver is 5V. Depending on the type of LED that you are using, I'd guess that you could string 3 or 4 LEDs in series with each paralled driver. Mount the drivers in a small waterproof box and that's all there is to it. No matter what the temperature or battery voltage, the LED current will be 50 mA.
I can't believe it has been so long since I have posted. I have over 3000 miles on the car, I think I love it even more now than when I first got it.
I'll just jump right in and share a few of my favorite pictures
I upgraded my rear view camera and screen. It's a huge improvement. The analog screen in the dash is now redundant so I'll be removing it and replacing it with a display for the gauges from the Megasquirt.
My air intake filters are on the bottom side of the car. They got way too dirty so I made air boxes to close them up and NACA ducts on the top surface for fresh air
I scanned the rear of the car and 3d printed new mesh pieces. The tail lights are also 3d printed. And yes, I'm still using the 1UZ
I didnt have good vision from my rear view mirrors. I realized it's necessary to have the mirrors extend past the sides of the the car to be able to judge if I'm going to hit an obstruction while backing up. So I designed and printed a new set. I maintained the turn signal in the mirror housing
The mirror vibrated more than I was comfortable with so I made small braces. In the background of the underside of the clam, there are NACA ducts and snorkels to direct the air directly into the intake tubes to keep out dust and hot air from the engine compartment
I still have a long list of things I want to work on. One of the most significant things I did was upgrade to the Xtracker hubs. The car was out of commission for a long time while I did that, and I still need an alignment, so the handling isn't optimal. But it's wonderful to be back on the road. I drive it to work most days when it's not raining.
I used clear PETG for the turn signal lens in the door mirrors. I tried using the same for the taillights but due to the complex shape I couldn't get the lens to print well enough to use. The back cover is black ASA and that printed great. A friend has a resin printer and he got a fantastic print for the lens. He used clear PLA which concerned me about durability and heat, but it has been fine. I painted the lenses red, which is what I did previously when the taillights were made from clear acrylic, and the paint is really good. This is my 4th or 5th design iteration.
When I say clear filament, it doesn't actually print clear. Maybe for a small cube, but not on complex shapes. The best you can do is translucent, but that's all I needed anyways.