Quarter inch is a little thick for a sill plate isn't it? How are these being made, are you making a mold and casting these out of aluminum or are you machining them?
save some dough You can save some real money if you get some aluminum, I would recommend 3/16" from a metal shop and you can usually buy it as scrap for a few bucks. If you have a router table you can make a pattern for the sill plate and even do roundovers and flutes just like a CNC. then you take it to a trophy shop or engravery and viola, an inexpensive and beautiful product that you can do a brushed or polished finish on very easily and then clearcoat them or even anodize or chrome them. I build a lot of one-off aluminum parts and sill plates are one of the easiest to do. The CNC pieces are nice but you can do it yourself for less and plus its a one of a kind piece no one will have. P.S. When you router aluminum make sure you wear eye and body protection and gloves. A particle mask too. I always make handles for my jigs so I have a good grip on the piece and ease into the material slowly so it does not kick. You can use regular wood bits too, aluminum is soft enough and the bits last a long time.
I didnt catch that 1/4" thick measurement. Have you tried a set on to make sure it dosent scrape the bottom of the door?
