TT Scale (1:120) Signals for 3mm LED

My brother and his kids have a nice TT scale modell train table. But they dont have any type of signals. I look for what I can buy, and the prices are not so cheap, or it is work with old style bulb. What is not so good, because you cannot repair it easy.
I decided to made my version. It is not so realistic, but it is looks good and easy to build!

I made it for 3mm leds, because it can be handled well, not as SMD types.
You can use any type of 3mm LED, I buy flat ones, this is looks better