We prefer not to do custom sizes, mostly because there’s no real need to. We bring the extrusions in already cut-to-length in 55-inch sections. We then cut and match 27-1/2-inch sections for shorter extensions. If a custom size extension is required, we can cut them to the desired length of 55 inches or less, but the pricing will remain the same as we’ll just end up with a weird length scrap off-cut. Contact us via email with the sizing requests. Standard extensions legitimately add either 55 or 27-1/2 inches of capacity, as the ‘dead space’ is already accounted for within the base kit sizes.