For the astable use pins 2 and 6 of the 555 need to be connected. I designed a jig in OpenSCAD and printed it in PLA.
I happened to have pliers which had the perfect width for the wire to be bent for this task. Quickly, the wire was bent for a lot of these wire bridges.
I fixed the jig to my desk using adhesive putty (the yellowish dots on the bottom of it). In this way, I could easily move it to a different position and it stuck again to the desk. This adhesive putty is one of my favourite tools.
Finally, I had a lot of prepared 555s.