SurfaceGui method
Step 1 : Insert a part then stretch it

Step 2 : Insert a SurfaceGui into the part then insert a frame into SurfaceGui

Step 3 : Select SurfaceGui then set LightInfluence to 0

Step 4 : Select the Frame then set the Size to this [1,0,1,0]

Step 5 : Change the BackgroundColor of the Frame to Green or Blue

Result

Neon Method
Step 1 : Insert a part then stretch it

Step 2 : Set the material to neon

Step 3 : Set the color to green or blue and lower the value to the
point where you can’t see the bloom effect

Result
