What is the best product for this project?

I have this art project idea. I want to create plaster blocks that would be decorative and hang on a wall. In the middle of the block, I want to have a flower or some other ornamental material "floating". By this I mean, preserved in a block of varnish or some kind of substance that would dry clear and leave the flower suspended. I do not want to flatten the flower, but for it to look almost as if it is trapped in a gl coffin, preserved. The only problem is I have no idea if there is a substance that will achieve that affect. Does anyone know of something like that, or have another idea?