We can make any dimensions you need. Often the long sides have narrow borders due to restricted space in the toe kick area. But there is usually a one inch wide border on the left and right for screw holes.
Pricing depends on the number of square inches, but it usually seems to run around $29.95 plus shipping. Call 509-535-5098 for a quote on the size you need. Please have your pattern opening dimenions handy as well as your desired overall dimensions.
Do you have a duct that is located between the baseboards at floor level? We are able to make a geometric register with exact overall dimensions to fit your space. Then we can laminate around the edges to give you enough thickness to where the front is about flush with the baseboard. Or we can make it sloping, like a traditional gravity baseboard register. Cost is $1 per square inch of overall dimensions. For example, a unit that is 14 inches wide and 6 inches tall would be $84, regardless of whether it is sloping or non-sloping and regardless of thickness.
please note that these are made from a high density plywood and the plys are visible.