The Vans RV7 design has about three inches of unused space between the side-by-side seats. So, I built an insert to provide storage for sunglasses, handheld radio, drinks, etc.
It is made of 1/4 inch popular from Home Depot that I ran through a planer taking it down to 1/8 inch thickness. The bottom and sides of the box were angled to match the cabin floor which is not flat between the seats. The cover shown above fits either of the longer compartments. The smalest compartment was sized to hold my Yaesu handheld. Overall it worked out well and is a snug fit between the seats.