I have been thinking about making my own boarderless easel. I can see using repositionable spray mount on a flat piece of plywood for RC prints, but what about fiber? I would imagine that the FB prints wouldn't law flat withough weight on the sides.
In the darkroom cookbook Anchell describes a "gelatin" easel. Where you have a wood base or container with hardened gelatin. The gelatin holds the paper completely flat, does not adhere to the paper and it lasts for long time. Neat uh?
I too have read about the gelatin easel, but there is a better way (maybe not as tasty though..)
You can buy a can of spray adhesive from Gepe that produces a surface like that of a Post-It.
It'll last for weeks, is reported to be ph-neutral, and when you no longer need it, it can be rubbed off.
It just sounds more practical than the gelatine method.
BTW, you can use this stuff inside of a film holder too. But you have to cut out the tracks first.