So one of my projects involved a whole lot of pcbs and I needed a quick way to attach to them for mcu programming but i didn't want to put a connector on each since connectors are quite often tight and hard to attach/remove (especially when brand new). I also didn't want to put a connector on these pcbs as there were for ID tags and a connector would look ugly.
So i added 6 round smd pads to the edge of the pcb (gnd,mois,miso,reset,sck,vcc) and made a DIY clip on probe to connect to the pads.
Using two 6pin 2.54 header soldered together some hot glue and a clothes peg.
The only critical construction factor is that you glue the header pins so they are at an angle to the pcb. This helps make sure they all make contact as the pin that touches first will bend back under spring pressure and allow the others to make contact.
Most programming operations are quick enough that you can just hold it in place - long pin headers (long enough to give some springiness - 10mm+) inserted into holes and held at an angle to get the contact pressure works fine.