The Simple $60 Spraybooth
DISCLAIMER: This article explains how I built a spray booth; it does not purport to explain all the safety ramifications of the tools and techniques involved. If you read this article and then go and saw your finger off or electrocute yourself or build something that eventually catches fire or otherwise harms your self or your property it’s not my fault.
When I built my first spray booth it was large and expensive because it was made from off-the-shelf items that I could put together with a minimum of tools and space. Back then I lived in an apartment and managed to put it together with my drill and my dad’s jigsaw.
Flash forward five years and I want to build a spraybooth for my brothers-in-law for a birthday present. I want to do it cheap because I also got them a compressor and some other miscellaneous hobby goods so I’ve spent plenty already…
Fortunately I’ve got a garage and some pretty good tools to work with now so I put this one together in a couple hours from $40 worth of stuff I got at Home Depot and some other stuff I had laying around. Depending how much stuff you’ve got laying around and if you have (or know) somebody with the right tools, you can probably make your own for $40-80.
Here’s what you need:
A 4’ by 8’ sheet of plywood like this, about $13:
You only need 4’ x 4’ but it’ sold in either 2’ x 4’ or 4’ by 8’ (get together with a friend and make two, you can help each other). I actually made this booth out of cheaper OSB board I had laying around (about $8) but it’s splintery and rough so I don’t recommend it, but I had it laying around:
Home Depot can cut your board in half to make it easier to transport and that won’t affect the build.
You need a fan unit for a bathroom, a cheap one will cost about $14:
You need some 3” x 8’ ducting ($9)
A 3-prong electrical cable ($4). I used one cut of an old printer power supply (one that goes to an old PC, monitor or power strip would work also),
but you could also splice an extension cord. If you really don’t want to leave Home Depot, they have a 6-plug power strip with a short 3’ cord for $4.
A couple of shelving brackets ($5):
Screws for your brackets ($2):
Some drywall screws (2 packs, about $2):
A cheap 25” x 16” x 1” air filter ($4):
Twist-on wire connectors ($1):
Here are the tools I used:
Circular Saw (one or the other would do, the table saw would be best for cutting straight lines)
Dremel with Roto-Zip (or a jigsaw)
Air Compressor with Brad Gun (a staple gun might work or a hammer and some very small nails)
Philips and Flat screwdrivers
I started by wiring the fan unit. Unfortunately I didn’t think to start taking pictures until after this was done. The fan unit does come with instructions of its own an I followed them to take the unit apart and get at the wiring. Then I grabbed my power cord. What I did was cut off the “mickey mouse” end of the cable I had. It was meant to plug into the AC adapter brick for an old printer I had. If you’re using an extension cord, cut off the female end.
Inside the cord were three separate wires. Strip off the outer insulation to expose the three wires inside and then strip off the individual insulation for each wire to expose about half an inch of the cable inside. The cord I opened up had green, blue and brown wires inside. The fan unit comes with green, black and white wires. Somewhere you can find wire color conventions on the internet for sure so look that up and figure out what you’ve got so you don’t wire up a short circuit and fry yourself.
What I did is make the assumption that in both cases green was the ground. I hooked those two up by twisting the exposed metal filaments inside the green wires and twisting a twist-on wiring connector onto them. Next, I had to figure out which was positive and which was negative. I twisted two wires together (one from the fan and one from the cord) and then plugged in the wire being VERY careful not to let all the loose uninsulated wires touch each other. I set down the fan unit and touched the two remaining wires together. DON’T hold these wires by the metal filaments! Once I touched them together, the fan began to spin.
As long as you’ve got the ground right, the fan will spin because one wire is positive and the other is negative so if you wire them up one way, the fan spins clockwise. If you wire them up the opposite way, the fan spins counterclockwise. I ultimately set it up so that the fan spun towards the black plastic exhaust pipe, otherwise I think you suck air in. Once you figure out which way the wiring should go, carefully UNPLUG the cord and then make your connections with the twist-on connectors. I also used some electrical tape to secure the cord to the wires coming out of the fan so that if the cord got tugged, it would be less likely to yank apart the connections and expose potentially live wires.
Next, draw your pieces out on your plywood. I made it look like this:
I chose 27” because it gave me enough room for a 16” by 25” filter to catch the overspray. You could go up to 29” and still fit on the board. Note the skinny strip, it will be the “roof” of the booth and to sit on top it should be thicker than the bottom and back because it should also go over the sides, and they’ll be about ½” thick each. If you want to go pro you can cut the front of the bottom ½” so it doesn’t stick out from the rest of the booth but I let it go on mine.
Cut the pieces out. I cut my board in half with a circular saw and cut the actual pieces out with a table saw. It helps to have another person to help you manage these large pieces of wood, but I did manage to do it by myself by putting a table next to my table saw and a box on top of the table at about the same height as the table saw to set the wood on and support it as I slid it through the saw.
Before you start putting it together, you want to take the back piece and cut out the square hole for the fan. I mounted my fan low and to the left because experience shows me that’s where my overspray goes, but if you’re a lefty I’d put it to the right.
Place your fan face down on the board and use a pencil to trace the shape of the fan (the metal box, not the plastic cover). Drill holes at the four corners big enough to either put in your Dremel roto-zip or jigsaw blade. Cut along the lines to connect the holes and you should have a square cut out that you can slip the lip of the fan box into (bend out the tabs on the fan box so it sits flush).
You can either mount the fan now or mount it after you put the booth together. I did it now. Get a 2”x4” piece of wood and cut two lengths about 10” long. Screw them together into a block with drywall screws (or use a 4×4 if you have one). Set the fan in place, set the block on the side of the fan with the mounting bracket and mark where you will put the screws and pre-drill some holes. Screw the fan onto the block and then flip the back of the boot over (so the fan is underneath) and put some screws through the block to hold the fan in place.
Next use the shelf brackets to put together the back and bottom. Don’t sit the back on the bottom, set it on the ground/table (whatever you’re working on). Put the short ½: screws in the shelf mounting screws pack into the bottom and file down the tips so you don’t scratch the hell out of wherever you put your booth. Use whatever screws on the back and cut them down when done (I actually used some machine screws and washers/nuts so I didn’t have a sharp screw poking out of the back of the booth).
Turn the booth on its side and glue one of the sides on with wood glue and then put a bunch brads through it into the bottom and back with a brad gun. Now do the other side. An alternative to all these brackets/glue/brads would be to use some 1”x1” strips along the edges and nail/brad/screw everything together.
Put the top of the booth on the same way. Put the front plate on the fan if you haven’t already. Use the duct clamp to clamp the 3”x8’ duct to the fan via the black header and stretch/bend the duct out a window or drill a hole in your wall and install a nice exhaust (one of these http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?langId=-1&storeId=10051&catalogId=10053&productId=202907381&R=202907381) or whatever works.