A 3D modeling studio that folds in your hands. TopMod Duo 4D shows TopMod 3D running on a foldable iPhone held half-open, like a handheld console: the model lives on the top screen, and every tool sits on the bottom screen under your thumbs.
What it is
TopMod 3D is a topological mesh modeler by AMAXIMAL for iPhone, iPad and the web. It grows out of the TopMod research on topological mesh modeling at Texas A&M University (Ergun Akleman and colleagues), where every operation keeps the mesh a clean, connected surface. That lets you punch holes, add handles, twist and subdivide freely and still end up with something you can render, share or 3D print.
The Duo layout is TopMod's answer to a folding screen. Bend the phone to a half-fold and the app splits itself in two. Lay it flat again and you get one big canvas with the normal layout.
How the split works
Top screen: look and pickThe full 3D viewport. Drag to orbit, tap a face to select it, pinch or scroll to zoom.
Bottom screen: the app you knowMenu bar, toolbar, Layers, Modifiers and options, unchanged. Tool panels open down here too, so they never cover the model.
Built-in touch padThe open space between the toolbar and the panels steers the camera, so your thumbs never have to leave the lower half.
Fold flat for one big canvasOpen it all the way and TopMod goes back to its single-screen layout.
What you can do with it
Model with topology, not just polygons. Create holes and handles, extrude, twist and subdivide in the style of the original TopMod.
Let the computer design. Topology optimization grows structural forms such as a table from loads and supports.
Make jewelry. Bejewel turns any mesh into a set gem piece with cuts you can swap, and physics lets you drop and play with the result.
Go hands-free. Camera hand tracking selects, extrudes, zooms and orbits with simple gestures.
See it in your room. Place your model in AR with Apple's AR Quick Look.
Take it out of the app. Export OBJ for rendering, other 3D tools and 3D printing.
The demos on this page
Open Settings on the viewer to run each one on the device: topology-optimized table, twisted handles, Bejewel with physics, hands-free modeling and AR. You can also turn and fold the phone, swap finishes and change the studio.
Screen budget
Inner display
7.6 in · 1878 × 2670 px
Each half, held portrait
≈ 1878 × 1335 px · 1.41 : 1
Outer display
Normal phone layout when closed
Get TopMod 3D
TopMod 3D is on the App Store for iPhone and iPad as “TopMod — 3D Mesh Modeler”. The Duo layout ships in version 3.9 and switches on by itself on a foldable screen; you can also turn it on any time from View ▸ Duo layout.
The bottom screen in this viewer is the real TopMod 3D app, not a video. The foldable iPhone is a concept model; the device and screen sizes are illustrative.