[dominique4]

Hi,

I'm an artist and work on an installation piece. Regarding to the concept of the exhibition, I use only plant based materials. I would like to make a transparent, epoxy-like stuff, which I can pour into a cast and becomes solid when dries out.
It also has to be somewhat durable. Could you recommend any materials?

Thank you for your help in advance!

Dominique

[ATMyller]

How hard and transparent in needs to be and can rest of the installation handle elevated temperatures?

A stiff agar jelly might work if hardness and high transparency is not vital.

If high temperatures are not a problem you can pour melted PLA over heated mould and vacuum the air bubbles out.

[Arkcon]

Well, I would use epoxy.  Because it is organic.   Its not in-organic. 

OK, addressing your topic seriously, now.  You really have to think carefully about what you want.  If you're looking for natural, plant-based materials, then they can only be as durable as most terrestrial plant life.  So at best you're going to get something like wood, but only if you use ... well, wood.

[Intanjir]

One of the more distinctive features of epoxy is that it doesn't set just because some solvent evaporates out. Instead the liquids react slowly to form the solid. This is essential to why it can come out so transparent.

If instead you have a system where lots of solvent evaporates out then this generally leaves behind small pockets of air. Unless these are extremely small(nano-sized) this will cause cloudiness. Even if they are small enough they will result in a bluish tint due to Tyndall scattering.
https://en.wikipedia.org/wiki/Tyndall_effect

If you want transparency then making use of pressure and temperature in your casting process will greatly increase the range of materials that can work. Thermoplastics can be made to conform their shape to a mold without having to add excessive additional material that when removed leaves cloudy air pockets.

For example, plant-derived Cellulose Acetate can be made into large transparent bodies, though often with a bluish tint.