An oilfield entrepreneur who could not afford a factory-built rig built a do-it-yourself drilling rig on a Diamond Reo truck frame. In remote oil fields, early oilmen often could not buy rigs locally because equipment and supplies were scarce, so this unit was fabricated from available parts so its owner could drill an oil well. Oilmen used high-explosive nitroglycerin to perforate geological formations at the bottom of a well bore so oil could flow into the cavity created by the explosion and then be pumped to the surface. A nitro storage safe allowed nitroglycerin to be stored safely in a remote area until it was needed to shoot and complete an oil well.