Flimsy Completed

I made one (to me, now) glaring error, but it was too late to change, so it is what it is.  I think on the whole it is kind of cute though.  All the geometrics kind of remind me of fencing to keep the little critters out of the garden.  
 I have a question for all you grammar geeks or English teachers out there.  What is the proper (or most proper) plural or possessive for a name ending in X ?  Would Maddox be Maddox's, Maddox', Maddoxes, or just plain Maddox.  I have started googling it, but haven't had time to really dig into it, and now I'm leaving to go to Orlando (about a 30 minute trip) to pick up one of my Grandson's from work. 
I ordered a folding table to use for a cutting table in my sewing room, and Walmart said it would be here between this coming and next Friday, but I got an email it is here today.   My book with RRCB in it is supposed to be here by Dec. 4th (I guess books get on the back of the pile at the US Postal Service as it was shipped a few days ago) and if I have similar luck with that, maybe I can keep up with my goal of having my Craftsy BOM, Maddox' (?) quilt and my RRCB all done before the new Easy Street mystery starts.  That would be wonderful.   If I do and I have lag time after working on Easy Street, I'll work on my Scrap Vomit (isn't that a horrible name), but if I don't I'll hopefully have the 3 more finishes by the end of the year anyway.
PS  We had a very nice day yesterday.  My son came and brought his dog and my daughter and one of my grandsons came and brought their dog.  We left the dogs in the back yard and went to a Mexican restaurant nearby that we really like.  Everyone enjoyed their lunch and the visit.  My husband, Ernie, probably wore himself out a bit, but I think that it was good for him and he enjoyed very much having his children (and his grandson) spend some time with us.   Everyone is so busy that we can't get together as much as we'd like, so it was a treat.