Portable Outdoor Projection Cart

A quick slideshow of my portable projector for watching movies and projection mapping outdoors. It is not a guide but I will offer some advice for what you need to get started. I used things that I had available (with the exception of the power inverter which I got a good deal on). I recycled a broken computer monitor to make all the mounts for the projector itself and the speakers as well. The projector mount is a quick-detach which allows me to move it between my room and the cart very easily and quickly (10 seconds each way).

This was a great way to enhance some of the camping trips that are more parking-lot style and also for just bringing down the streets out of town to set up in the city for fun at parks or anywhere.

Necessary things:

1. Projector. Any brightness will do but I would suggest that you aim for 2000 lumens (or brighter). You can mount the projector however you want. I used special salvaged parts to allow easy detachment and reattachment as well as the ability to tilt the projector up and down.
2. DC-to-AC power inverter. This is what makes it portable with the battery since it needs an AC power source and we are giving it a DC power source. The rating you need for your projector is dependent on the power draw of your projector (check its datasheet). I would aim for an inverter capable of twice the wattage (W) of your projector to account for the high initial power consumption of the projector on start up. You will attach the back side of the inverter to the battery, and on the front side you can connect any electronics you want (starting with the projector)
3. Battery. A car battery is what we are aiming for here. The more amp-hours it has, the longer you can project. You will have to calculate this out for your specific projector's power draw. (If you need help, PM me or comment below). It is also worth mentioning that there are different types of batteries. The one I am going to selectively point out is a marine deep-cycle battery. This is what I have and used and it works amazingly. I can project for about 4 hours on a fresh charge. You will also need jumper cables to connect the battery to the inverter.
4. Speakers [optional]. Any speakers will do, you will just have to figure out how to connect them. I used an old set of Bose speakers that I had that haven't been used for many years. I used a cheap ($2.50 from ebay) amp / inverter that required a 12V DC power supply. Conveniently, that is exactly what our car battery does! You could also plug them into the inverter output if you want / need.
5. Cart. To assemble the cart I used scrap wood from the dumpster, a salvaged monitor, and some wheels I bought on clearance at Menard's hardware store. I tried using a moving dolly but it broke the wheels on concrete roads and railway tracks broke the rest. So use larger wheels if you can, and add something to steer (mine isn't that easy to steer with just a rope).  
6. Laptop. You will need a way to play movies (or whatever) so a laptop is the easiest way. You will also need a VGA or HDMI cord to connect to the projector. The laptop fits easily on top of the inverter and can further be powered by the inverter at the expense of some projection time (the laptop doesn't draw as much power as the projector).

*Over time I have collected most of these items but to go out and buy all of this would have been quite expensive.