The most time-consuming step is using acrylic pour painting techniques to create a random, multicolored background to simulate stained glass. Search the internet for instructions on this technique. There are various styles and artists who recommend different materials. The bottom line is that you mix each color of acrylic paint with a pouring medium (so that it runs freely across your board) and a little oil (so that the colors do not mix). For something like this, I use the cheapest paint and school glue cut with water as a pouring medium.

During assembly, I use a basic wood glue that dries clear. Tweezers are helpful when positioning the small accent pieces.