A PowerShell utility script that outputs C# code listing all custom fields in the RootWeb of a site collection (filtered by a field name prefix) as a set of static classes with constant string properties for Id and Name.

FieldsToConstants.ps1

$siteUrl = "http://site/collection/url"
$fieldPrefix = "ClientName_"
$outputPath = "c:\temp\Fields.cs"

$site = Get-SPSite $siteUrl
$fields = $site.RootWeb.Fields

$output = ""
$newLine = "`r`n"
$tab = "`t"
$fields | Sort InternalName |
	Where { $_.InternalName -like "$fieldPrefix*" } |
	ForEach {
		$output += $("public static class " + $_.InternalName.Replace($fieldPrefix, "").Replace("_0", "TaxHTField") + $newLine)
		$output += $("{" + $newLine)
		$output += $($tab + "public const string Id = `"" + $_.Id + "`";" + $newLine)
		$output += $($tab + "public const string InternalName = `"" + $_.InternalName + "`";" + $newLine)
		$output += $("}" + $newLine + $newLine)
	}
$output | Out-File $outputPath

$site.Dispose()

FieldsToConstants_Output.cs

public static class AgeRange
{
	public const string Id = "12b9b899-04c2-47c5-bcf9-cf9ee5055099";
	public const string InternalName = "ClientName_AgeRange";
}

public static class AgeRangeTaxHTField
{
	public const string Id = "29244be4-988e-454d-a1b3-e8f8c08317c8";
	public const string InternalName = "ClientName_AgeRange_0";
}

public static class AnimationType
{
	public const string Id = "bf620570-8866-4334-a791-63635aaed4a2";
	public const string InternalName = "ClientName_AnimationType";
}

public static class AnimationTypeTaxHTField
{
	public const string Id = "85cf3e96-858d-499c-958f-f7c58ddcd3aa";
	public const string InternalName = "ClientName_AnimationType_0";
}

public static class Channel
{
	public const string Id = "d15f5cda-a4ea-4980-af8f-022556311f28";
	public const string InternalName = "ClientName_Channel";
}

public static class ChannelTaxHTField
{
	public const string Id = "1b27d38c-19a6-4f6a-bb17-0bff2f037a54";
	public const string InternalName = "ClientName_Channel_0";
}