Attempting to operate the Source SDK Hammer Level Editor in the Source 2006 engine for Half-Life 2 Deathmatch currently results in an error of: "Missing material, ...verify that your game directory is correct." If you have this problem, read on! This is a Source SDK bug caused by Valve and this is a work-around to fix the issue and operate the game in the Source 2009 version of the engine.

The cylinder method!

A modified version of Zoner's compile tools (aka 'p series'), which contain CSG and RAD improvements over the originals

Forklift truck, with driver seat cover

Tool for browsing GCF files- these are Steam's version of the 'PAK' file. May also open Source game .gcf files too.