When you have to create stairs and distribute them in an architectural model is a common problem to put them on the right height, this tool will allow you to easily position and distribute stairs. To launch it you just need to drag the file over your 3dsmax window. And it will automatically open the tool dialog box.
Normally we start having lines of the plane that represent each one of the stairs, we need to apply an Extrude Modifier with a negative value. The negative value on the extrusion is very important, because the height of each step will be calculated based on the pivot point position of each step. So if the extrusion were positive the height of the step would be the one defined on the tool plus the height of the extrusion.
Before pressing any button on the tool, it is necessary to select the steps in the order that you want them to go, from bottom to top. To accomplish this task I usually use the paint selection region tool, just because I think is easier.
Once selected you can enter the increment value, which is the default option, next you need to press the distribute button, in this example each step was moved .15 m on the Z axis.
If you would like to try different values for the step height, first you need to press the Reset to 0 Button before changing the increment Value and press again Distribute.
You can Use the second choice on the script called by max height, in this mode you can specify the height at which will reach the last step. In this example the max height value was set to be 3 m, so when you press the distribute button the last step will reach exactly to 3 M.
In the case when steps + 1 option is checked, the last step will be 1 value below the max height, this is because to choose the height of each step, it will divide the total height between the number of steps plus 1, and this will be the height that it will give to each step.
There are cases when you want to put stairs on a second floor, or to start your stairs from a different height than 0, in this case there is a button called Get Z min, that will allow you to click on any scene object and capture its height. In this example I click over the pink box that is the roof of the first level, or the floor of the second level, which makes the text of the button change to Z Min = 30.
Next I will press the reset to Z min button, and this will move all the steps to a value of 3m, from there we can press again the distribute button to position the second floor. If we would like to try different heights we could again press the Reset Z min button to change the value of the max height or increment, and try again with distribute to set the steps height.
You can freely download the script to position steps from the following link.