Can't say I've actually gotten this question but it seems that you comparing it to your dh's workshop was a good comparison. I would just tell him that it is a hobby just like his rebuilding old trucks are and that you will know what you are going to do with them after they have been created and speak to you. It's your hobby (I might even say maybe a passion?) and you should have a creative space where you can go and not have to keep cleaning things up and put everything away at dinnertime, bedtime, guests, etc. He has a place for his stuff and you should too. Also, remind him that it isn't just quilts that you can be creating; there are other smaller projects that can be made quickly for gifts and spiffying up the house.

Lobby hard for that sewing room! You deserve it.

Ginny B