Hi Kerene,
What a neat project! Yes, you can make mosaic tiles out of resin.
First, you will need to select the size you want. We have a few rectangular and square mold sizes here:
https://shop.resinobsession.com/collections/molds/rectangle
https://shop.resinobsession.com/collections/molds/square
Once you get the size picked out, you will then need to mix and measure the resin to pour into the mold. Color and/or add things as desired. This tutorial isn’t exactly what you want to do, but it will give you ideas on basic techniques: https://www.resinobsession.com/resin-tutorials/how-to-make-a-bottle-cap-resin-coaster
It sounds like you are new to resin? If so, I would recommend these beginner articles too: https://www.resinobsession.com/tag/beginner They will help you get started with basic techniques and what to watch out for to make sure everything goes well. Good luck!