Me too, but I am also very tempted by the Yamaha TRBX505 or even the 305 which is just over $300.
When all said, it is only for me to get a feel for 18mm spacing on a 5er.
If it's just for feel and you are going to go custom, then just grab the Yamaha. Maybe even a used version would be available. Yamaha's don't get all the great press, but they're almost always very solidly built instruments that play like something more expensive.