Another interesting option is to take advantage of companies producing a precast concrete items. This can be as simple and quick, but also as expensive, as buying a precast room or building.

These are used for rural equipment that has to resist heavy weather, vandals and the occasional hunter's bullet. Telcom and cell sites use these as do remote radar sites. Many manufacturers sell precast rooms that are rated to 150 mph winds and UL 752 Level 4 ballistic rating that covers a .30-06 Lead Core Soft Point bullet. Higher wind and ballistic rating are usually available as non-standard items with proportionally higher costs. This is a quick and easy way for those who are flush with cash.

Another alternative would be to buy a higher turnover precast item like a large septic tank and to adapt as either complete shelter structure or interior for an exterior concrete pour. An advantage to this is that standard tanks are usually delivered with a lift truck that will swing it into position for you. Once in position you finish interior and exterior or you rig spacers and a exterior pour form and then call in the concrete truck.

Another alternative using precast concrete is to buy standard precast concrete poles. Think of them as 8" x 8" x 8' reinforced concrete logs that you stack like you are building a log cabin. The US Army experimented with building bunkers out of these units and showed that you could stack and pin them together to build highly capable bunkers. Each log weighs about 600 pounds so a small crane and strong friends are going to help. The Army would horse them into position using a half dozen strong backs to haul each piece and build the bunker using nothing but hand tools, sweat, and harsh language.