What is a spray booth anyway?

Basically – spray booth is a ventilated box used to exhaust the paint vapours outside. Pretty much a must-have if you’re planning on airbrushing anything stronger than acrylics. Unless you want your house to smell of chemical warfare.

As with everything, you can easily buy one. Many modellers however choose to build their own instead.

First off – it’s cheaper. Small spray booth that actually does its job will run you at least $80. Bigger ones – $200 and up. DIY ones can however be made for as little as $40.
Secondly – building one yourself, you can customize it to your needs. Size, proportions, lighting, other extras – everything is up to you. Maybe what you need is a tiny, collapsible booth you can store easily. Or one big enough to serve as your entire workspace. It’s all up to you.

Personally, I decided I want to use lacquers and enamels even before buying airbrush setup. Right after getting it, I started checking out YouTube videos and other blogs, looking for ideas.

RG 1/1 Twin Turbo Spray Booth ver.Blaze

I came up with a few points I wanted my booth to fulfil:

• All the materials must be available locally, so I can make sure it’ll fit the design. Either bought from a hardware store or salvaged from something I no longer need.
• It must be big enough to work comfortably.
• It must be sturdy and, if possibe, somewhat presentable. No ductaping fans inside badly cut holes etc.
• I should be able to disassemble it (at least partially), in case I moved or needed to store it for a long period of time without using it.

Once I had a basic idea of what I wanted to build, I rushed off to the store. I spent a good while checking out and test fitting various plastic bins and fans. I returned home with a bunch of supplies and rough design, which would keep evolving until the very last day of the build.

Many builders made their spray booth using box-shaped bathroom fans. Sadly, they were not available where I live. I went with cheap 125mm fans instead. 215m³/h seemed like decent performance, but I decided to install two, just to be sure. This decision complicated the build quite a lot.

Before I move on to WIP shots, here’s somewhat complete list of the materials I’ve used:

 

Building spray booth – the beginning.

 

Using Olfa CMP-1 compass knife I cut holes for the fans in the back of main chamber. Using compass knife for cutting plastic this thick is quite a pain and takes a while, but I didn’t have a better alternative.
To be safe, I cut the holes just short of 125mm diameter.  I used woodcarving file to widen them a bit, test fitting the fans every couple passes. Side note: Don’t use woodcarving file. It’s not designed to shape plastic. As a result I ended up cracking my box, as you can see by the tape. Eventually I fixed it with transparent epoxy glue.	My QA specialist checking the fit.
Next up, I started working on the front plate. It would go inside the box as a mount for the filter. Using the box cover as a guide, I roughly traced shape of the box onto the plexiglass sheet.
I used a jigsaw to trim the sheet somewhat close to the shape I wanted. I also cut out the middle, making sure the opening was smaller than the paint roller grid that would hold the filter. Using angle grinder I started slowly trimming outside edge.
Took me 2-3 hours to get the front plate to fit neatly where I wanted it to be. At this point I really wished I bought a box in a more regular shape.
At this point I started working on the back chamber. Its purpose is to collect output from both fans into a single 150mm exhaust hose. Furthermore, it acts as a stand for the entire spray booth. First off, using 150mm connector I traced a circle onto the side of small box.
Again using Olfa CMP-1 I cut out the circle, just short of 150mm diameter. And yes, I did use woodcarving file (and later on some more epoxy glue) again, for the very last time.
Eventually I found some grinding bits in the garage, so I used those to finish the fit.
With that piece done, I could finally get an idea what would the spray booth look like once finished.

Building spray booth – new challenges appear!

Finding a way to actually connect the boxes was quite a challenge and something I did not think about ahead of time. It was quite problematic since back wall of the big box was also irregular. Therefore to make the back chamber airtight I had to level it somehow. Finally I decided to use another sheet of plexiglass to create a backplate that would cover entire back, providing more than enough flat space.

I started by tracing the fans onto plexiglass, matching the slots in the back wall. Within those I drilled in a couple of holes for the jigsaw.
To avoid cracking the plexiglass, I cut the circle out bit by bit rather than entire thing at once.
Downside to that approach – what I ended up didn’t resemble circle as much. While the second one turned out better, final fit also left much to be desired. The gap between fan and plexiglass in the first one was just too big.
As they say – third time’s the charm, so I scrapped the entire sheet and started over. While the process was almost exactly the same, I went at it much slower. I kept shaving off only 1-2mm at a time with the jigsaw and finished the fit using a newly bought metalworking file. It took quite a while, but as a result I ended up with two perfectly round slots for the fans. The fit was spot on.
Quite a few things happened since previous step here: First off, using the big box as a guide I drew the final shape I wanted for the backplate. I also installed a light switch for the fans and glued a window seal around the edge of small box. You can also see aluminium profiles I cut that would hold it in place later on.
Using the jigsaw, angle grinder and a bit of manual filing I got the backplate into the exact shape I wanted.
I drilled holes on both sides of those aluminium profiles. While at it I also filed down the rants so they don’t interfere.
With profiles as a guide, I drilled through the backplate and the big box. Using coupling nuts I bolted backplate to the box, creating mounting points for the back chamber.
Finally, I bolted down those profiles, using them to hold the small box in place. Quite surprising how well it turned out.
Using some wire leftovers I connected the fans.

At this point the booth was ready for a test run!

Building spray booth – wrapping up.

At this point all I had to do was to install the filter and exhaust hose. Rather than think of something new, I simply repeated what I did with the back chamber.

To install the filter I first cut the handles off both grids. Next I measured and cut two pieces off another aluminium profile that would hold them in place.
At this point I thought of creating some handles on the frontplate, so I could take it out easier. Figured those U bolts would do the job. I thought using silicone glue around the grids was a good idea, but it proved more trouble than it was worth. Eventually I replaced it with window seal.
With everything in place, I marked where to cut bolts and profiles. Left like this, they would probably end up wrecking either my hands or my airbrush when painting. Probably both. This brush pen is what I’ve used to trace and mark pretty much everything during this build.
Trying to limit the air getting sucked in around the frontplate I added some window seal around its edges.
Similarly, I added some on the inside of the box.
As the last step, I installed the exhaust hose. I considered using silicone to glue it to the back chamber and keep it airtight, but it’d go against my principle of being able to easily disassemble the spray booth. It fit more than well enough and stayed in place on friction alone.
Finally, with everything assembled, it was time to test the performance.   I think it passed.

 

I’m quite happy with how it turned out. Performance is more than good enough – I can spray lacquers and ditch the respirator a minute later. Admittedly it takes quite a bit of space, but I never intended to build a compact booth to begin with. As intended it’s easy to disassemble for storage though. Entire thing can be disassembled within ~5 mintes, using nothing but 10mm wrench.

If you’re looking to build your own spray booth, I hope this post helped you somewhat.

 

Finally – I’d like to take a moment here to thank my dad, for entrusting me with his workshop, his entire power tools stash and some great advice along the way. Thanks dad, you’re the best!

Also kudos to my dog, for chilling in the workshop with me night after night, enduring all the noise and my power metal playlist like a boss.