Decide how big you want the RV to be and get an appropriate size vehicle. If you want a small vehicle with not much more than a bed, a minivan might suffice. It is more likely, however, that you will need a larger van or even a bus.
Pull out most, if not all, of the rear and middle seats in the vehicle. One or two seats can remain, especially if using a bus, if you are planning to use them in conjunction with one of the RV's rooms like a dining room.
Place the bed within the vehicle. This can be as simple as a sleeping bag on a pile of foam cushions or other soft materials. If you construct a whole wooden bed frame, bolt and secure it to one inner side of the vehicle, preferably close to the vehicles front or rear.
Build a kitchen within the vehicle using a table and small, compact appliances. Bolt the table to one side and secure a microwave and/or toaster oven under the table with a portable electric cooking range on top. A small camping stove can also work as long as the propane canister is secure when stored and the RV has plenty of ventilation when in use.
Add a sink to the kitchen using a small table with a hole cut into it and a stainless-steel bowl placed inside the hole. Connect a pump and drain system to the sink bowl if you have experience with plumbing, or just store jugs of water to pour into the sink; you can remove the bowl and dispose of the water outside.
Assemble the dining area by bolting another table to the wall opposite the kitchen and securing chairs next to the table. You can also use foldaway chairs and store them under the table; only use the dining room when the RV is stopped.
Build bathroom facilities only if you have the space and extensive plumbing knowledge. This will include installing an indoor toilet connected to an outside septic tank and possibly a shower with a drain and pump system. You may also want to build walls to enclose them.
Include entertainment devices, such as a stereo and flat-screen TV with a video player and possibly a game console. These can be stored in RV cabinets that you can mount to a side wall.
Supply sources of power for everything from the kitchen appliances to the entertainment devices. Use deep-cycle batteries with power inverters connected to them. To keep the batteries and inverters safe, build boxes to store them in and screw these boxes in the RV.
