How do I plan a 3D relief before I start modeling, so the pieces go together in the right order?

Why a plan matters

The model in the 3D View is built by combining every visible component from the bottom of the Component Tree to the top. The contents of each Level are combined first, then the Levels are combined with each other. So the order and the Combine Mode you pick decide the result, and a plan made on paper saves a lot of rework. The official user guide's advice is to break a complicated design into pieces until each piece is simple enough to manage. Its example is a bunch of grapes: every grape can be its own component, the whole bunch can be one component, or the grapes can live on one Level with the leaf and stem on another.

Steps

1. Finish the 2D artwork first. Every closed outline is a future component.
2. List the parts from back to front. The background and base go at the bottom of the tree, the foreground at the top.
3. Pick a Combine Mode for each part from how it overlaps its neighbor. The official guide's rule of thumb: a shape that sits completely inside another is usually Add (or Subtract for a recess). Shapes that only partly overlap are usually Merge. Low is the rare case of recessing a shape into a raised shape.
4. Give each depth layer or subject its own Level (border, background, main subject, lettering). Levels have their own Combine Mode, which controls how everything on that Level meets the result of the Levels below.
5. Model the large simple forms first, then the details that ride on them. In the official sign example the dome comes first, and the leaf and border are added to it.
6. Adjust with the dynamic properties (Shape Height, Base Height, Fade, Tilt) instead of remodeling. They can be changed or reset at any time until the component is baked.

Pro tips

• Set the job size only as large as the part. Modeling Resolution is spread across the whole job area, so a small model in a huge job loses detail.
• For a symmetrical design, build one half or one quarter inside a Level with a Mirror Mode (see the entry on Mirror Mode).
• Leave sculpting for last and do it on a copy (Aspire only; see the entry on Create Component from Visible Model), so the structure you planned stays editable.