Check with some of the builders. They might sell you what you need.
Aluminum bar of this dimension is very hard to find. I think even the builders have to special order it in bulk or cut it themselves. Not sure, but I think most of them use just a tad wider strips, maybe 5/16 or 3/8.
Apron and neck Inlay trim , why use 1/4th inch aluminum , most mfg's use 1/16th or 3/32 inch by 1/2 inch by 36 inch's long , you can get that at a local hardware store , also it doesn't need to be aluminum either , look at sho-bud