First Project, i'm fell like i'm idiot. XD

[Pentapinguin]

Hi guys, i'm new here...my name is Gianni and i'm from Italy...I always wanted an xwing racer drone (250 class) so now i'm trying to make it by myself...i started the project on tinkercad just to waste a couple of hour while i was waiting the customer but then i finished it...i'll learn some better sofware in future (any advice on that?).the problem is that i have to split it in 4 to print it but meshmixer leaves the cuttted parts as an empty shell and this is waht i get if i try to slice it. this is the complete model:completo.stl.jpgthis is what i get from plane cuts in meshmixer:frsx.stl.jpgThis are how it looks in cura 3.5.1 and what i get if i try to slice it:frsx in cura.jpgstampato.jpgi really hope some of you guys can help me, i don't like at all the idea to start from the beginning.I attached the stl file. feel free to use it as you wish.