Unplated would probably work. We used an aluminium honeycomb in ours and that works great. Remember to organise a good extractor for your laser or you'll spend hours cleaning the mirrors, as it is count on cleaning them at least once a week or if it's stood unused for any length of time.
That is good advice - both the extraction and cleaning. Extraction is not only needed to clear the fumes from the cabinet (which can become combustible) but also to clear the smell!!! Burning styrene, wood or acrylic is not good for the nostrils...not to mention your lungs!!! Just be careful that you don't extract straight into your neighbours windows!!!
Our machine came with a very powerful extraction unit and a 4" dia flexible pipe. Additionally, the laser is cooled by water circulating through the laser tube. It is paramount that this water is kept cool otherwise your laser tube will have a very short life. Again, ours has a water chiller unit - like an air-conditioning unit - which keeps the water below 22 degrees C. Using the laser for a number of hours at a stretch can heat the water dramatically. If you don't have a chiller unit, then stand a large thermometer in your tub of cooling water and keep an eye on the temps. As for water - use only distilled. Again, any hardness in the water will shorten tube life.
For cleaning, it was recommended to me to use pure alcohol on cotton buds for the mirrors and focus lens. Baby wipes for the rest of the machine. And a wipe over with 3 in 1 oil on the sliding bars.