Not really worth it to open yet another DIY vias thread, so I'll go eco-friendly and reuse an old one.
Now, whereas actual vias are pretty straightforward -- just drill some holes, insert a wire with a closely matched diameter and solder it on both sides -- making holes for through hole components that sit flush against the board *and* must connect to traces on the component side, i.e., making the trace contact points hidden, is not so easy.
One way is to drill a slightly bigger hole to accomodate the component's pin and a piece of wire, then solder the wire on both sides, then insert the component and solder it too. I haven't tried this, and, while it sounds feasible, it also sounds very tedious and error prone.
Another way is to use rivets. There are brass rivets like this that come in different sizes:
They're
available on Aliexpress.
I ordered some to try. The smallest size is 0.9 mm (the tube part) claimed, more like 0.95 mm actual, getting wider towards the flange, so probably will need 1 mm holes, but may as well be 0.9 mm, depending on how it will comply under pressure.
Inner diameter for the smallest ones is just above 0.5 mm.
Easy to solder, they're tinning very well (and solder is very easily sucked into the tube, which is both good and bad).
My plan, given that I don't have a tool to properly install them (to tighten and flatten on both sides), is to insert them from one side, press with something with a flat end (e.g. a drill bit) to flatten as far as it can go, then solder on that side. The other side can be soldered after the through hole component is inserted and cut just like a regular lead.
However, the flange diameter is relatively large: flange OD in the 0.9 mm rivets is 1.9 mm. While this is fine for vias (unless the board layout is very dense), it will not work, especially with the bigger rivets, for through hole components, unless they have widely spaced pins: for example, the 1.3 mm rivets have inner diameter just large enough for the 2.54 mm pitch pin headers, but at the same time their flange diameter is sufficient to short neighboring pins.
There is a workaround: the flange can be simply cut (using some good wire cutters) along the sides facing the adjacent pins, which will provide the required clearance. But this is also a somewhat tedious work, though it can be acceptable if the number of THT components that require such "plated holes" is low.
Has anyone found any better rivets or small tubes that would have really small flanges -- just large enough to prevent them from sliding into the holes? Aliexpress is notorious for poor search results relevance, so I may have simply missed something suitable.