# Sketch First, Then Build: How Flux Turns an Idea or a Photo into a 3D Device Describe a device or show Flux a photo. Flux draws a concept sketch around real parts, then uses the sketch as the reference for the 3D model. Three real examples. Written by [Matthias Wagner](https://flux.seobdtools.com/natarius) Published Oct 2026 - 4 min read ![Sketch First, Then Build: How Flux Turns an Idea or a Photo into a 3D Device](https://flux.seobdtools.com/p/assets/blogs/sketch-to-3d-device/main.webp) Every device starts as a picture in someone's head. In most workflows, that picture goes through many hands: a sketch, a design brief, a CAD model, a board. Each handoff loses a little of the idea. In Flux, you tell the agent what you want, or you show it a picture. It draws a concept sketch first. You change the sketch until it is right. Then Flux builds the 3D model from that sketch, in the same project as the electronics. Here are three real examples. ## One sentence in, a concept sketch out The full prompt was: *"build a smart expresso scale"*. Flux did not draw a picture right away. First it asked how the scale should work and gave four directions, from an ultra-compact drip-tray scale to a scale that stops the espresso machine at the target weight. We picked the ultra-compact scale. Flux then wrote a project specification and an industrial design brief: a 100 × 95 × 15 mm drip-tray body, a 2 kg load cell, a 0.96 inch display, touch pads for tare and timer, and a 500 mAh battery with USB-C charging. Then it drew an exploded concept sketch of all of it. ![Exploded concept sketch of a smart drip-tray espresso scale, with each part labeled](https://flux.seobdtools.com/p/assets/blogs/sketch-to-3d-device/espresso-sketch.webp) Every label in the sketch comes from the brief: the load cell, the battery bay, the display window, the USB-C port. The sketch is a picture of the device you are about to engineer, not a mood board. ## From sketch to a solid model The prompt: *"Create a 3D soap dispenser as an everyday example of smooth organic curvature, with a rounded body flowing into a narrow neck and curved spout."* Flux drew a concept sketch of the form: a pear-shaped body, a smooth neck, and a curved pump spout. ![Concept sketch of a 180 mm soap dispenser with a smooth body-to-neck transition](https://flux.seobdtools.com/p/assets/blogs/sketch-to-3d-device/soap-sketch.webp) Flux also built the model as editable solid CAD: a body and a separate pump head, about 182 mm tall. You can download both parts as STEP or STL. ![Solid CAD model of the soap dispenser body and pump head](https://flux.seobdtools.com/p/assets/blogs/sketch-to-3d-device/soap-cad.webp) Because it is real CAD, you can check it like real CAD. The curvature map in the Flux 3D View shows how smoothly the surfaces flow into each other. ![Surface curvature map on a sculpted soap dispenser in the Flux 3D view](https://flux.seobdtools.com/p/assets/homepage-v2/pcb-3d-analysis-curvature-map-dispenser.webp) Next we asked: *"can u design the pump mechanism too please"*. Flux did not guess. It asked what soap the pump must move (liquid, gel, or foam) and if we want to print our own valves or fit a purchased pump cartridge. ## From a photo to a walking robot The prompt was a photo of small walking robots and one line: *"Lets design a full robot like this one"*. Flux read the photo: a servo-jointed biped with big feet, a camera-like eye, and colorful body panels. It also said what the photo cannot show: dimensions and internal hardware. It recommended to start with a leg-and-balance prototype, because reliable walking is much harder than an expressive head. Then it drew a concept proposal. The notes on the sketch are engineering decisions: five joints per leg, a fall-arrest line for the first tests, a power disconnect, and electronics marked as a mockup until they are designed. ![Concept proposal sketch of a walking companion robot with engineering notes](https://flux.seobdtools.com/p/assets/blogs/sketch-to-3d-device/robot-concept.webp) After we approved the concept with *"lets go"*, Flux started the lower-body CAD, the controller electronics, and test firmware in parallel. Its own checks found real problems, and Flux reported them: the knee adapters collided when the legs bent, and the torque margin was too small for the assumed mass. The first legs also drifted from the sketch. They became tall, straight stacks. We wrote: *"the robot legs don't look exactly like in the setch...fix that"* and asked for sketches from all sides. ![Front, rear, left, and right concept sketches of the same walking robot](https://flux.seobdtools.com/p/assets/blogs/sketch-to-3d-device/robot-elevations.webp) Flux used the four views to check the proportions, the joint positions, and the bend of the legs. For the surfaces that must mate, it used the dimensions from the manufacturer, not estimates from a picture. The robot is not finished. It is a real prototype in progress, with a list of open checks. That is the point: the sketch keeps the idea, and the engineering keeps it honest. ## Why sketch first - **A sketch is fast to change.** You can try a new shape in a minute, before anybody spends a day on CAD. - **The sketch is built on real parts.** Flux draws the product around the board and the parts in your project. - **The sketch becomes the reference.** When you accept a sketch, Flux uses it for the silhouette, the proportions, and the control layout of the 3D model. Hard limits, such as board size and connector positions, still come from the parts. - **Everything stays in one project.** The sketch, the brief, the 3D model, the board, and the firmware live together. A change in one is visible to all. ## Try it Open a new project in Flux and try one of these prompts: - "Sketch a pocket-sized air quality monitor with a round display." - Attach a photo of a product you like and write "Design a device like this one." - After you approve a sketch: "Build the enclosure in 3D from this sketch." ## About the author [Matthias Wagner](https://flux.seobdtools.com/natarius) Founder & CEO at Flux Matthias is the Founder and CEO of Flux, a hardware design platform that's revolutionizing how teams create and iterate on circuits. Find him on Flux [@natarius](https://flux.seobdtools.com/natarius). Let’s start building Build your big idea together with Flux. All you need to do is describe what you want to make, or what problem you want to solve. Flux will work with you to make it a reality. ![Close-up photo of a PCB made with Flux, with an ESP32 module, buttons, and a microSD slot.](https://flux.seobdtools.com/p/assets/blogs/miscellaneous/sidebar-cta-pcb.webp) [Try it Free](https://flux.seobdtools.com/signup) ## Related Content [ ![Teal technical illustration of a circuit board and enclosure with hand-drawn circles and arrows](https://flux.seobdtools.com/p/assets/blogs/markup-mode/main.webp) ### Circle it. Ask Flux. 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All you need to do is describe what you want to make, or what problem you want to solve. Flux will work with you to make it a reality. [Try it Free](https://flux.seobdtools.com/signup) ![Close-up of a Flux-designed printed circuit board](https://flux.seobdtools.com/p/assets/homepage-v2/mission-visual.webp)