i have looked into various ways of fixing a PCB to a front panel. Glue? metal bracket or nylon slot
I use a couple of methods, if I’m attaching a paper panel to the faceplate I countersink holes and fit M3 bolts into the panel, these are then covered over by the paper panel.
When I had real panels made of aluminium printed this was a problem as had no standoffs available and had to again drill holes through the panel and put the M3 countersunk bolts through and paint them black to hide them against the panel.
Lastly I have cut strips of perf board about 1cm wide and glued them together to the height I needed and used them as standoffs glued between the front panel and the board, not the best solution, but it can be levered apart if need be and there are no holes in the front panel.
Metal brackets are my favorite
I prefer PCB spacers with the hexagon shape, especially those made from brass. They can easily be fitted on a panel in the middle of a square of sockets and switches. The biggest advantage for me are that they make it possible for the PCB to hoover above all sockets and pots, thereby saving space. A downside is that by having the PCBs flat is that you are limited in size of the PCB.
I usually cut (as long as needed) pieces from an L shaped PVC profile. The PCB/stripboard is attached to the profile using hotglue, screws, or zipties and onto the panel using glue (hotglue or superglue depending on how how heavy the PCB is). I avoid metal L brackets because they are harder to work with using handtools and because of the hassle to have an extra layer of insulation to avoid shorting the back of the PCB. You can see an example here where I was able to mount quite a few heavy components (1000μF capacitors, regulator with heatsink, etc) onto the prototype panel with just a couple of drops of superglue here. Longer profile pieces also work nicely to provide support for thinner front panels.
So far this has worked fine for prototyping, but in the near future I will upgrade this method by using wider profile pieces in order to eliminate the use of glue. This way I can secure the L profile pieces in between the front panel and a potentiometer, jack, or switch, and onto the PCB using M3 screws and nuts.