Firstly, this fits perfectly, as pictured. I was blown away by that to be honest. Rollercoaster Lego is expensive and this is an awesome way to extend a set or prototype a larger MOC. Secondly - also as pictured - at the lower end of the underside of the upwards curve, where much of the support was, is pretty rough. My PLA probably wasn’t optimally dry, and that might explain the layer lines… but I think some of it is just a function of the supports.