There are several different ways to build lasers. The idea behind it is very simple. First, you make a pixel of clone and select PHOT from the menu, and then click on the pixel of clone.
Essentially, when clone touches Photon, it reproduces them endlessly in exactly eight directions. The trick to producing a laser, is to limit a piece of clone to producing only -one- direction of photons out of those eight.
By surrounding the clone with void after it's been told to produce photons, you can easily limit the directions that the photons can pass. A thickness of at least three pixels is generally wise, considering that the normal speed of photons is exactly three pixels per frame.
Photons can pass through clone element as well, which means that clone that produces photons can be lined up with other clone, and so long as there is space between the pixels, the clone pixels will not interfere with one anothers' photon production. As a result, they can be stacked horizontally or vertically, and the photons will pass through the additional clone as if it's not present at all.
...Then, in a more recent build of powder toy, the element Powered Clone was introduced, which has the ability to produce photons consistently on every frame (most of the time.)
In addition, you don't need bulky wall gates to control them because they can be switched on and off using PSCN and NSCN.
To heat photons you merely have to make them touch something that itself is hot or cold, or pass through something hot or cold, and they will transfer that heat to the next object they touch.
Edit By ads999: Here is the basic jist to make a laser, hot or cold. Feel Free To Copy. https://powdertoy.co.uk/Browse/View.html?ID=638917