I've always used sticky Industrial Strength Velcro to affix my pedals to my pedalboard.
And it's always bugged me that I might be seriously depreciating the future value of my pedals with Velcro gummed to the bottom, covering serial numbers, country of manufacture and useful 'avoid exposing unit to excessive moisture'-type information.
Scouring the net for anything I could find on 'attaching pedals without Velcro' yielded one dude who used individual bicycle chain links, attaching one eyelet to the pedal baseplate and screwing the other eyelet down to the woodbase of the pedalboard. An elegant solution by itself, and certainly rock-solid.
My Voodoolab RotoVibe, RMC wah and Boss volume pedal already have sticky Velcro I attached years ago to their baseplates so they are mounted to the Pedaltrain in the usual way.
Go ahead and try this at home, folks!
And here's my earlier review of the Pedaltrain Jr. pedalboard.