HOME MADE PLASTIC FILLER
You can make your own plastic filler, we used to do it along time ago. You take the plastic trees that the parts come on then cut them into about 1/8" sections then put them into a small wide mouth glass container and cover them with testors liquid cement and leave till it disolves the pieces forms a thick plastic paste. Great for filling seams. You can make the filler the color of the model by useing the trees from that model or other model of the same color. It does take longer for the filler to harden but when it does and is sanded out it's almost invisable