Replacement base for a smoke alarm

A smoke alarm in our house is held onto its base by two thin tabs of plastic that eventually broke. I found a design on Thingiverse by buwprinter (from Germany). It was obviously not made for my model - there are zillions out there - but I thought it might work. It was provided as an STL file, not a modifiable design. MatterControl has a scale feature, but it's an overall resize not intended for specific accurate needs. So I had to learn a couple of things in order to resize it accurately in Fusion 360:

• How to import a file.
• How to scale a mesh design.

The overall shape and appearance of the base is not that important. What matters is the spacing of the locking tabs that hold the alarm in place. I measured that carefully with calipers and then used the scale ratio feature and hoped for the best.

Also, this was the first time I was switching my printer from a high-temperature plastic (PETG) to a lower temp (PLA). I had heard that this could be an issue, so recently I bought some cleaning filament. It's an odd size, so you don't feed it through with the motor, you push it by hand. I was surprised how much I had to push through before the result was fully clear with no trace of green from the PETG.

I noticed that the PLA was not extruding straight out but rather curling up as if it were sticking on one side. I had to scrape the outsize of the nozzle to get rid of some scorched debris, and also tried some advice about pushing and pulling filament getting out a few times until getting a nice clean "cone" on the end. Seems to be printing OK now.

The diameter of the locking tabs came out perfect, but each tab was a bit too long for the slots. I ground off about 1/8" from each with my Dremel tool and then it locked on just fine. Here's the final result: