I Kind of Regret the XTool Enclosure 

Make sure you have sufficient fresh air flow from the other side of the house into your room, the fan creates quite the under pressure in your room, and the same amount of the air you vent out, has to come in.

I agree... I have the similar setup (I have the extension but have not installed because I have the 40w upgrade and waiting for xtool to send me the longer cable needed, so I will be having similar issues soon). The smell just doesn't go away with just the exhaust fan - I'll look into your additional fan - good idea. Things get REALLY bad if you cut acrylic - I need to make sure that I am leaving the enclosure closed with fan on for at least 10-15 minutes before I open the enclosure, otherwise the smell escapes.

Venting is a must for health and better all around enjoyment. I did three things: 1. An enclosure with a powerful evacuation fan .. ducted outside. 2. Sealed the room, around doors, windows, vents. 3. Place a fan to draw replacement fresh air into the room. By sealing the room and drawing fresh air into the room, I created a slight positive air pressure outside of the enclosure. This helped keeps the smell and smoke contained within the enclosure and gave the evacuation fan time to work. No smell no smoke.

Spot on. Smell is the biggest issue I have so far. I put the xTool enclosure away and bought another brand. I also purchased an in-line fan as well (195 cfm). Didn’t spend too much on the fan as I was expecting it to be a throw away. But I am on the look-out for a much strong fan that will be worth the $$ and to hopefully answer the smell issue. So I’ll will be watching what other might post here.

I have the same aftermarket 4" fan and it moves a ton of air. I completely got rid of the included fan and increased the size of the hole to fit the new 4" duct. I also put the fan as close to the window as I can so I have as little duct on the output side of the fan. I found that there were some pin holes in the duct and smoke would escape from there. The new 4" fan also needs a ton of fresh air intake in order to work. I cut out spacers and my enclosure sits up about 1/2" inch from the table allowing more fresh air into the enclosure ensuring maximum efficiency of the fan. Being in a smaller room, you may want to have the door open a bit so that the air can move out of the enclosure taking smoke and smell with it. I do not have the issue of my Xtool enclosure smelling. Start by removing the small fan completely and increasing the size of the hole to accommodate the 4" duct. You can get 4" adapters to fasten to the enclosure and attach the duct on Amazon. Hope this helps

There are a couple of things you can do to mitigate the smell. First, do NOT open a second window. Even though you are trying to blow the air out, that air has to come from somewhere inside the room, and because the enclosure is NOT airtight, it will pull fumes through the cracks into the room. Second, be sure to seal around the window vent insert and joints. Use a good gasket material around the window insert, and saran-wrap or a heat-shrink plastic around the joints in the hose at each connection point. There will always be a little bit of odor left due to the residue coating the inside the enclosure - that's just the nature of burning things. But following the two suggestions above will significantly reduce the odor, making the room easier to work in while the laser is running.

Kind of in the same boat with my Ikier enclosure. It's nearly the same, just a different brand. The default fan does a decent job venting outside the window. I barely smell anything while the machine is running. Once I'm done doing my occasional tiny jobs I let the fan run for an extra 10 to 20 minutes to clear up as much as possible. But that does not seem to help much. The moment I open up the enclosure the same day or even a week later without doing any other jobs, a force of odor/smell "smacks" me in the face. I've been cleaning and moving away parts inside the enclosure to my attic to see if the smell inside the enclosure would reduce but no luck so far. Been thinking about a upgrading to a stronger in-line fan or trying to make my own enclosure. For the latter just not sure what kind of orange window I need to be safe.

Can you give me the outside measurements of the extended enclosure. I'm building a work bench and I need to know how big to make it. Thanks in advance.

I wonder if running the fan in the window as outflow is pulling available airflow from the intake on the enclosure. Think of two trucks pulling on each other. The infinity may have a higher cfm but not if it is pulling against the window fan. Just a thought.

The air inlet on the left hand side of the standard enclosure allows a toddler to look straight at the laser. I noticed this myself because my enclosure is close to a window, which reflects the blue light right at my eyes when the laser works on the left hand side.

Do you still run the original fan in addition to the AC Infinity fan running them both at the same time?

My main issue on the blue light, smell and smoke is all around the air intake area on the enclosure. The blue light does bounce/come through vent and I'm looking at what options I have for that. The smoke is also an issue if you set up your work piece close to the air intake and I think this is partially to do with the air assist adding enough "push" to drive it out instead of the fan pulling across the enclosure (the added fan to pull may help tho). The smell, like you mentioned, really depends on the material. I just leave the fan running and the enclosure closed for an extra min or two after the job is done. The biggest issue, on smell, has been when you're burning off that paint/top coat/etc of things; for wood/leather, I've found that to be minimal, even with the default fan.

Have you thought about getting a fume extractor? There are a bunch for reasonable price.

forget sealing the enclosure, u actually dont want to do that. you NEED for air to get into it, otherwise your exhaust system doesn't do anything. Instead you want to expand your exhaust system. bigger fan, then bigger hose, going from 3" to 4" makes a big difference from 3 to 6" is even better. plus bigger fans means lower noise level.

It would have been nice to have a 120mm fan instead of the 80 mm. I bought a 6 inch duct fan and made an enclosure with boxes dot py.

After going 'round and 'round with xTool to honor their warranty on a16 day old xTool Air Purifier that had crapped out AND plopping down serious coin on a Filtrabox Micro I discovered this: the smell is from crap plywood full of glue/formaldehyde/arsenic/plutonium/ the bodies of dissidents etc. when i stopped burning cheap wood from the big box home stores and hobby stores my situation imporoved a brazillian percent! my situation: 20w d1pro in the basement with ZERO way to vent outside. The xtool thing worked fine until it didn't. the FILTRABOX MICRO is the cat's ass!! Once xtool replaced their air thingy, well, i use it in the background, in my "spray booth" since it's quieter i use it at night to prevent other "burning wood" smells from circulating.... just sayin' I quit burning crap wood and life got better. OH! i exhaust the enclosure with the filtrabox. THAT exhaust is kinda sweet actually....