Algodoo

use a laser with a much shorter length, attached to the poston itself. you'll need a mechanism to avoid premature piston firing, giving opposite effect. or, if you can't fix that, try to convert that engine into an astinkson engine or similar

EDIT:when spawning stuff, use := in the code instead of =

why use := instead of =?

because, in thyme, := works for declaring variables(new geometries/things), = changes the variables(existing stuff), and == checks if the variable is equal to another value(If-statements). you can view more by opening the file thyme.cfg, with notepad

sorry to pester you, but what are the actual practical affects of that?

if you use the wrong command in different situations, it might affect other objects(namely the own object with the onX(collide/laserhit/hitbylaser) script)...
example: let's say you want to spawn an object with a different variable. in this case, self-collision(HeteroCollide, in script menu). if you use a = in the spawn script, you can end up changing the spawner's self-collision variable, causing a recursive(AKA, Fork Bomb) crash. if you use a := it will spawn the objects themselves with the different self-collision setting.
:= declares a variable
== scans a variable(Equal to if-statement infix)
= forces the variable.
when you're spawning something, you are declaring a new geometry, so, its attrubutes should also be declared.

Thank you RA2Lover you are very helpful