Run OpenSCAD from PowerShell

This guide shows a reliable pattern for calling OpenSCAD from PowerShell, based on a production-style script that builds command arguments dynamically.

It covers:

  • Setting paths
  • Building -D parameters safely
  • Passing numeric and string values
  • Running OpenSCAD with Start-Process

Prerequisites

  • Windows + PowerShell
  • OpenSCAD installed (example path below)
  • A .scad file you want to render

Minimal Working Example 

$scadExePath = 'C:\Program Files\OpenSCAD\openscad.exe'
$scadScriptPath = 'C:\path\to\model.scad'
$outputPath = 'C:\path\to\output.stl'

$cmdArgs = "-o `"$outputPath`""

# Numeric parameter examples
$cmdArgs += " -D `"Diameter=50`""
$cmdArgs += " -D `"Wall_Thickness=2.4`""
$cmdArgs += " -D `"Transition_Angle=45`""

# String parameter examples (note nested quoting)
$cmdArgs += " -D `"Style=`"`"hose`"`"`""
$cmdArgs += " -D `"Measurement=`"outer`"`"`""

$cmdArgs += " $scadScriptPath"

Write-Host $cmdArgs
Start-Process $scadExePath -ArgumentList $cmdArgs -Wait

If you have many optional settings, use a helper function to append arguments only when a value is present.

function AddArgs($cmdArgs, $value, $argValue) {
    if (![string]::IsNullOrEmpty($value)) {
        $cmdArgs += $argValue
    }
    return $cmdArgs
}

$scadExePath = 'C:\Program Files\OpenSCAD\openscad.exe'
$scadScriptPath = 'C:\path\to\model.scad'
$outputPath = 'C:\path\to\output.stl'

$style = 'hose'
$measurement = 'outer'
$diameter = 50
$transitionAngle = 45

$cmdArgs = "-o `"$outputPath`""

# Numbers
$cmdArgs = AddArgs $cmdArgs $diameter        " -D `"Diameter=$diameter`""
$cmdArgs = AddArgs $cmdArgs $transitionAngle " -D `"Transition_Angle=$transitionAngle`""

# Strings
$cmdArgs = AddArgs $cmdArgs $style       " -D `"Style=`"`"$style`"`""
$cmdArgs = AddArgs $cmdArgs $measurement " -D `"Measurement=`"$measurement`"`"`""

$cmdArgs += " $scadScriptPath"

Write-Host $cmdArgs
$executionTime = $cmdArgs | Measure-Command {
    Start-Process $scadExePath -ArgumentList $_ -Wait
}

Write-Host "Done in $executionTime"

How Quoting Works

OpenSCAD expects each define in this form:

  • Numeric: -D "Diameter=50"
  • String: -D "Style=\"hose\""

In PowerShell string literals, backticks are used to escape quotes, which is why string parameters look like this:

" -D `"Style=`"`"hose`"`""

Common Mistakes

  • Forgetting to quote string values passed to -D
  • Not escaping quotes correctly in PowerShell strings
  • Omitting -Wait on Start-Process when you need synchronous execution
  • Building args in an array and then accidentally passing malformed joined text

Optional: Include Output File Conditionally

If you want to support preview runs (without writing .stl), make output optional.

$setFilePath = $true
$cmdArgs = ''

if ($setFilePath) {
    $cmdArgs = "-o `"$outputPath`""
}

$cmdArgs += " $scadScriptPath"
Start-Process $scadExePath -ArgumentList $cmdArgs -Wait

Template You Can Reuse 

$scadExePath = 'C:\Program Files\OpenSCAD\openscad.exe'
$scadScriptPath = 'C:\path\to\model.scad'
$outputPath = 'C:\path\to\output.stl'

Function OpenSCAD-AddArgs($ArgName, $ArgValue) {
    write-host "ArgName: $($ArgName) ArgValue: $($ArgValue)"

    if ($ArgValue -eq $null) {
        return ''
    } elseif ($ArgValue -is [string]) {
        if (![string]::IsNullOrEmpty($ArgValue)) {
            return " -D `"$($ArgName)=`"`"$($ArgValue)`"`"`""
        }
    } elseif ($ArgValue -is [int] -or $ArgValue -is [double] -or $ArgValue -is [decimal] -or $ArgValue -is [long]) {
        return " -D `"$($ArgName)=$($argValue)`""
    } else {
        throw "unsupported type $($ArgValue.GetType().FullName)"
    }
}

$style = 'hose'             # string
$diameter = 50              # number
$length = 40.45              # number

$cmdArgs = "-o `"$outputPath`""

$cmdArgs += OpenSCAD-AddArgs -ArgName 'Style' -ArgValue $style
$cmdArgs += OpenSCAD-AddArgs -ArgName 'Diameter' -ArgValue $Diameter
$cmdArgs += OpenSCAD-AddArgs -ArgName 'Length' -ArgValue $length

$cmdArgs += " $scadScriptPath"

Start-Process $scadExePath -ArgumentList $cmdArgs -Wait

If your script has many parameters, keep one AddArgs line per OpenSCAD variable. That makes it easy to compare PowerShell names to .scad variable names and quickly troubleshoot missing values.