The softened diagonal lines indicate that the edges art not coplanar and to create the surface, additional edges are required. That comes down to fundamental geometry. In the plywood for your climbing structures, you could induce a bit of twist to compensate. Not in SketchUp however. Follow Push/Pull from Joint Push/Pull Interactive would thicken the geometry and provide the miters along the seams. [image: p0Fh_Screenshot-8_17_20185_03_29AM.png] You would still need to make each panel a group or component. I would make them components with Replace Selection with Component turned off. That will allow you to use the miter faces and edges in each neighboring component. You'll have the components in the In Model library to drag out so you can lay them out for nesting. Your profile indicates you are using SketchUp Make but you need to be using SketchUp Pro for this work.

Michelle, more questions are certainly OK. You're right. It is sometimes unavoidable that faces get split. When they do, however, that is your clue that the outer edges are no longer planar. If you were to build the structure with a plywood skin, you could probably torture the plywood a little, bending it to screw down the perimeter but it would be stressed that way. Obviously if you carry that too far you'll either break something or have to divide the panel into smaller pieces. In SketchUp a face must be flat. There's no bending a single face as you could with plywood. As far as fixing the broken faces, you can move edges and vertices if needed to return the edges to planarity. [image: k4QO_flat.gif] It might be in some cases better to rotate some of the edges about the hidden edge is the right thing. You could also trim to intersecting faces as in your second screen shot. In your last one, you can't make that shape without the triangles because the edges aren't in the same plane. This shape is similar to a boat hull. If you look at plywood hulls, they are developed from multiple planks. There is some bending and twisting that each plank can tolerate and when it's all assembled, the hull is very strong but there is a limit to how much bending you can put in. Thus the need for multiple planks. Again, in SketchUp all edges must be in the same plane to get a face between them. It shouldn't create any problems for you, though. You could use a different program that uses NURBS for modeling. You'll not be working with flat faces as in SketchUp but it won't give you a good representation of your plywood-skinned structures.