How to convert your standard car to oxygen fuel in ten easy steps.

Three days
A car
Two junk bikes
A disposed drafting table frame
A motorcycle or some other front wheel system
A few friends that can wreck stuff fast
A few friends that can build stuff fast (may or may not be the same friends)

Tools needed (in order of importance):

A sawzall
A welder
Big hammers
Drills and bits
Various wrenches and sockets
A grinder with cutoff blades
Screwdrivers
Hole saws
A chop saw
Measuring tapes
Marking tools

Step 1. Trade
If your car is like most cars, it has a lot of stuff that won't be necessary after conversion. These may include, but are not limited to...

engine
transmission
windshield
dashboard
front wheels
doors
airbags
gas tank

The easiest way to dispose of these unneeded items is to give your car to a junk yard. Most junk yards will be happy to exchange a running car for an empty shell. This saves you a lot of time and hassle. The need for special tools is drastically reduced. Make sure that the junk yard will deliver your shell to your work space for you.

Also, try to get a car with and keep:

Rear wheels
A parking brake that works
A good battery
Some lights for nighttime use

Step 2: Primary demolition
Invite your destructive friends over. If you tell them you're demolishing a car, you'll get lots of people interested. Pizza and beer can help.

The first things to destroy are the dangerous things. The gas tank, if still there, should be dropped and put far away. All remaining glass should be removed. If you still have air bags, carefully dispose of them.

Next, remove some crap: Seats, switches, hooks, seat belts, dash board, etc. Most of this stuff will unbolt. For the rest:

Step 3. Hammer
Whatever doesn't unbolt, or will just be cool to hit with hammers, gets hit with hammers until it's not on anymore.

Step 4: Preliminary Sawzall
Using a combination of hole saw/sawzall, start cutting weight out. The floors can go, most structure can go, anything over five pounds can go. Remember, "It's not like we're going to be pushing this thing sixty..."

Step 5: Start planning
Yes, planning is all the way down to step five. Push things together and see if they'll fit. If there's something in the way, cut it out.

This should finish Day One.

Step 6: Bracing
Remember to invite your constructive friends today. Once things start looking like they might actually fit together, tack weld them in place. Don't overdo Step 4. The front wheel should go in now so its supports can hold the remainder of your car together when the firewall comes out.

Step 7: Put the bikes in
The bikes should be attached to the car, but able to pivot both horizontally and vertically. Weight of the car should not be on bike wheels. Pivots allow the car and bikes to turn and roll over uneven terrain seperately and not stress each other. Weld the parking brake in somehow.

Day Two's probably done by now.

Step 8: Fine sawzall
Use the sawzall to remove more weight, to clean up edges, and to make feet, pedals, heads and bike tires clear. The grinder might be helpful.

Step 9: Fine demolition
Knock off all those useless little pieces that somehow survived to step 9. This may include taking off weird tape, glue, and fabric; lots of little bolts and nuts; wires, radio and computer stuff; and stuff that didn't seem as fun to hit with hammers.

Step 10: Details
Take the remainder of your three days to:

Paint the car frame
Get some lights working
Put on bike bells
Make stickers