My parents have been using their cheap market PC for almost 10 years now. It still runs well and they have never complained, but obviously a pre-emptive strike is needed.
Their office room is decorated with a wooden antique table (not shown on photos) and other similar furniture, so I wanted to make something that would blend in. Sadly, since I live in a block of flats, I have neither the tools, workspace or skills for woodworking, so I had to improvise a bit.
A few euros got me a nice roll of DC Fix adhesive film with a nice wooden texture. I only used a small part of the roll, so the modding budget is maybe 1 euro.
Next I needed a case that would be reasonably small and it should have smooth surfaces for easy installation of the adhesive film. Any fan grills should not be covered and poking a thousand holes cleanly would be impossible. Luckily a Fractal Design Node 202 was a perfect fit, since the vinyl could be applied in one large piece around the entire case. The main fan grill (top when in vertical stand) has a thin seam around it, so the vinyl gets a clean cut. A hair dryer can be used to stretch the vinyl around edges. The case can be used both vertically and horizontally.
As for the components, nothing fancy. I wanted as few cables as possible, so a M.2-SSD and a fully modular SFX-PSU (so cute!) were easy choices. Solitaire my father plays is not a very demanding game, so an integrated GPU is more than enough. That leaves half the case empty, in case parents need a PCI slot for anything. AMD 2200G runs smoothly, but the stock cooler (Wraith Stealth) is just horrible with noise. Even on fixed low rpm the noise is patchy, so no fan curve can fix it. I will replace it with NH-L9a later (not shown in the photos).
And yes, a "gaming" motherboard was the cheapest ITX board available when not considering the ones with integrated CPUs. (the prices are not accurate)