I agree with RB. Using toothpicks is very clever. I used to always feel like I was cheating when I would use non paper items on my models and then I realized it does not matter and does not take away from how impressive something is. After all, you are building a screen acurate Y-Wing out of toothpicks and pizza boxes....thats awesome!
Great build so far. I have an unbuilt, Fine Mold plastic model of the y-wing that has been collecting dust since I started building models out of paper. One of these days.
I still cant believe this is your first complete scratch build, the detail is spot on from reference photos I have seen. Are you going to be building an interior for this?
It looks good also here will a picture insert as soon as my phone is fixed.
Also i made a try with the main engine body...
but that is a lot of thinking to get the correct shape out of it.