Yes. If you haven't already figured this out, there are numbers of how-to-do-it posts here starting with the "Featured Answer" at the top of this thread. Because Houzz displays only part of the Featured Answer, you want to click on the faint "read more" line to get Houzz to display the rest of that detailed post by Luna123456. Also, there are something like 1.1k additional posts in this thread, most of which are not initially displayed. On my computer, I have to display all the posts before I can do a full search of the thread. Houzz makes you look below the "Featured Answer" to find the fine print which currently reads "see 1037 more comments." You may have to click a "See more comments" several times to get Houzz to display all of the posts. Then you can do a terms search (CTRL-F calls up a search box on MS Windows computers.) That will get you the posts with recommendations on specific brands of detergents and oxy liquids to use with DIY refilling.

As for the stability, obviously you do not want something made out of 1/4 inch plywood. Find a good, experienced carpenter, tell him what it will be used for (say, this is the application ...), and inform him you need it to be built to the same specifications as the floor to which it is fastened. That includes vibrations and loads. None of this is rocket science, an experienced carpenter will know what to do, including how to satisfy any local code requirements. Anything located not in your basement you will want a drain pan underneath. For extra credit (may bust the $400 budget) I'd put a rubber mat between the drain pan and the flat, (perfectly) level surface of the platform/pedestal/cabinet. Here's an example, this one will need to be cut to size. I've seen them for a few dollars less somewhere. BTW, a perfectly flat surface, and perfect leveling the machine (and checking the level every so often) is one key to minimizing any effects from the vibrations, ... rocking movements of the machine, sounds, vibrations in your home's frames, floors and walls. And to a lesser extent long term wear and tear on the machine itself.

I got my w1/t1 set in January to replace an old top-loader. I didn't get the TwinDos version. Our clothes have never been cleaner. The whites are whiter, stains I thought were permanent have faded or disappeared. I'm very happy with these machines. Since the coronavirus outbreak in my hotspot city, I've been selecting the "pre-wash" and "extra rinse" options on every load, pushing the cycle time up to 2.5 hrs. The heat pump dryer is excellent - I adjusted it to our soft water and it dries clothes quickly. A load of towels and bathmats dry in under an hour.

You can use bleach the problem is that the slot in the pull out drawer where you put the bleach does not get flushed into the washer during the main wash. It is a software bug. the work around is to add the bleach to the main detergent slot after the washer does it’s first flush of that drawer. You only get a couple minutes to do it, but thst is a work around. Most people who switch to oxygen bleach dont go back to chlorine bleach. OB could be Optical Brighteners or Oxygen Bleach. Optical Brighteners are chemicals that reflect only certain colors of visible light. This tricks your eyes to thinking things are white. They do nothing to actually clean clothes. Many people have allergies to optical brightening chemicals and they are usually considered an environmental pollutant.