I think that is a really nice, thoughtful idea, and I personally would love to receive such a thoughtful gift, but I think you need to be honest with yourself about two things:
1. Are you artistically talented? Will you be able to do a professional enough job of the painting?
2. Is your friend the kind of person to appreciate home made gifts?
I say this because I once made a friend a wedding gift instead of giving them the money they had asked for. I didn't feel comfortable giving them money as I prefer to give something more personal, plus they are very well off and I had already spent a small fortune in time and money attending her 4-day long hen do and their wedding which was miles away and mid-week!
I did what I considered to be a professional job of making the gift and it was something thoughtful and personal. I also spent quite a bit buying good quality materials to make it with so it wasn't as though I was just going for the cheap option. However that is the only wedding gift I never received a thank you card for
I am not sure whether that is because they didn't like the gift, or just didn't send thank you cards, but either way still very rude not to send thank you cards
In hindsight, she is not really the kind of person to appreciate home made gifts or thoughtful touches.
My best friend gets married in April, and I have been thinking about her wedding present. I am quite creative, so not keen to go down the "wine glasses off wedding list" route and want to make her something a bit more personal.
I was thinking about painting a quote about love from her favourite book onto a canvas. In the colour scheme of her living room or bedroom.