Many owners of ABJDs and related dolls try to not just leave them sitting on a shelf somewhere but create a miniature environment for them to ‘live’ in, though given most dolls are greater than 1/3rd scale I doubt the term ‘miniature’ really applies.
In many instances it’s possible to use pre-existing furniture from model or doll shops, or creatively adjust existing things such as desktop organisers that contain small drawers or shelving; there are also some decent jewellery boxes styled as wardrobes like Mele (available from some gift shops), or small drawer-units of inlaid lacquer such as Doore Art (here in London they have a stall in Camden Market, which also has lots other things that can be used as props), but otherwise the options are limited unless you decide to make your own, which isn’t as difficult as it may first appear.
These guides are aimed at those who are either new to basic woodwork or, like me, haven’t done anything for over 30 years (screwing together flat-pack bookshelving doesn’t count, either!). They are also far more of ‘what to do’ rather than a ‘how to do it’, as everyone has their own way of working, whilst anyone with any real skill can jump straight to the end of each section and go “huh” before making it properly. ^_^
In my case, there is a long but narrow table in my bedroom of 1.8m × 0.6m (= the girls’ room using existing walls), with a slightly wider table of 1.8m × 0.9m in my spare room (= the boys’ room, also doubling as the lounge with changeable wall panels); both tops have been faced with 30cm square parquet-effect vinyl floor tiles to create a neutral space that can be covered with rugs and so on.
As for the actual shape of the furniture, that’s entirely your own choice, but if you’re not sure of what will look nice, the best thing to do is visit stores and / or browse catalogues, for at the very least you will see things that you know you do not want, which is always a good start.
Note that the quality of the wood (or in many cases the lack of quality) can be a determining factor in which mouldings and sections are used, thus limiting the design even further, as can the available stock. Here in central London, shops such as Homebase and Leyland only have products from a company called Richard Burbidge (pronounced G-A-R-B-A-G-E), whose wood is often bent, twisted, sheared, warped, riddled with knots, or oozing sap (often all in one piece!), never mind that they position very sticky labels up to 30cm from one end, so carefully examine all sections before buying them, and store them horizontally, don’t prop them up in a corner where they can bend under their own weight, and avoid under-floor pipes that feed radiators. Also be aware that many sections of 2.4m have a join in them, so take a measure and ensure that the longest piece you need will fit, as the grains will never match otherwise; if later painting the furniture, this isn’t so important.
Whilst it would be very nice to just take the dimensions of existing full-sized furniture and divide by 2.75 or whatever scale you want to use, boy dolls in particular have long legs on bodies that are already somewhat thin, and even without their almost mandatory platform boots stand very tall.
The simplest way to determine how large to make anything is just use the dolls as a guide, propping them on books or other supports as necessary so their thighs are roughly parallel to the ground: this gives a distance to the top of the cushion or mattress, whilst drawing around their legs and bottom will give a basic size for a cushion. Laying the doll down will provide the mattress’s length, with its width depending on whether you’re making a single, double, a king-size, etc; if mixing differently-sized dolls, then the largest obviously takes precedence. Once the cushion or mattress size has been fixed (foam bought from a local market came in 25mm, 50mm, & 75mm thicknesses), everything else can be designed around that, taking into account space for padding on the underlying frames.
If you have access to one of the many 3D modelling & rendering packages that are available on a variety of platforms (old versions are sometimes given away on magazine DVDs, and some are free from the net), then everything can be done virtually before ever cutting real wood, thus saving many headaches later, though don’t limit yourself too much as things may come to mind during construction that can be used to make improvements (or mask mistakes!). Otherwise, the old-fashioned way of sketching or drawing on graph-paper will suit almost as well. Before you even do any of this, however, visit the hardware store and see the sizes and shapes of wood sections that are available, as it’s rather pointless designing something which can’t then be made.