Several years ago I was at the funeral of a former monk. When the last of his parents died he was obligated to leave the monastery to take over the family business. He remained single and lived a quasi-monastic existence all his life, reciting the Divine Office every day. Our schola chanted at his funeral. The coffin was made of plain, rough, unfinished plywood and 2x4 framing.
I’ve made it known to my family that I do not want an expensive casket that will end up in the ground until dissolving into worm food. I hope that one or all three of my sons will build me a coffin, from scrap plywood and 2x4s we have back of the shed on our property
My mother was cremated and was in a combustible container. We only brought the urn to the church. I was fairly new back into the Church back then so AFAIK what I was advised in the parish office was OK.