Brand Design on a Budget: Google Stitch, Design Principles & Live Split Testing — Conversion Monthly

In this Conversion Monthly, Danny McMillan is joined by Dorian and Matt Kostan (no Sim this episode — he's on holiday) for a live, practical session on building brand-quality design systems fast and for free. Dorian opens with a tight crash course in the three design fundamentals that separate professional Amazon listings from amateur ones: font pairing, grid and layout, and colour theory. He then demos Google Stitch live, building a full design system from a wooden utensil listing in real time. Danny shows a more automated route — using Perplexity to control Stitch autonomously and generate a complete brand kit from just a product title, bullet points, and a reference image. Matt rounds it off with a live Product Pinion split test of the new designs against the original listing — and the results deliver the session's sharpest lesson. The big takeaway: pretty is not enough. Information + design working together is what converts. Key Topics Google Stitch for brand design — Free AI design tool that generates full brand guidelines, font pairings, and mockups from reference images and prompts 3 design fundamentals every seller should know — Font pairing, grid and layout, colour theory with a contrasting action colour Perplexity + Stitch autonomous workflow — Danny demos letting Perplexity control Stitch end-to-end with zero manual input to generate a full brand kit Coolers.co — Free colour palette tool with a visualiser and AI colour bot (Matt) UX and design laws applied to Amazon — Miller's Law, Fitts' Law, Jacob's Law, Occam's Razor translated into listing and brand site decisions Product Pinion live split test — New designed variants vs the original listing, with real shopper results in under 10 minutes Live test result — The original information-heavy image outperformed the prettier redesigns early on; lesson: strip information at your peril Timestamps [00:00] Intro — Danny opens, Sim is out, format overview [00:48] Dorian: Why most Amazon listings lack design consistency [02:00] The 3 design principles: font pairing, grid/layout, colour theory [04:30] Font pairing explained — serif vs sans-serif, how world-class brands use them [07:00] Colour theory — complementary colours plus one contrasting action colour [08:30] Live Google Stitch demo — wooden utensil set, design system generated from brand brief + images [10:00] Stitch output: colour palette, font pairings, layout mockups [12:17] Matt: brand guidelines used to cost $1,000+ — now free in Stitch [13:00] Dorian: live Figma iteration — cleaning up the infographic using new design system fonts [17:00] Matt: information hierarchy lesson — measurements vs benefits on infographics [19:30] Dorian: "mouse text" and anchoring — what to leave in, what to strip out [20:33] Matt: Coolers.co overview — free colour palette generator and visualiser [22:00] Matt: UX/UI design principles applied to Product Pinion and Amazon listings [25:12] Danny: Perplexity + Stitch autonomous brand kit demo — Z Kitchen brand from scratch [27:00] Z Kitchen outputs: design system, A+ content, infographic, lifestyle mockups, packaging concepts [31:00] How to iterate inside Stitch — refine vs reimagine, varying only specific elements, up to 5 variants [36:00] Danny: UX design laws — Miller's Law, Fitts' Law, Jacob's Law, Occam's Razor [40:00] Danny: Typography slides — spacing systems, layout balance, font families [43:32] Dorian: reveals three redesigned variants ready for split test [44:35] Matt: launches live Product Pinion test — 50 shoppers, cooking category targeting [47:33] Live results coming in — original listing leading over new designs [48:00] Dorian: "pretty is one thing but the information has to be there" [49:00] Danny: design and information are two separate layers — both are required [51:30] Product Pinion API + Claude integration teaser [52:36] Final results and wrap-up — test completed in ~10 minutes with 50 real shoppers [53:44] Closing thoughts and Seller Sessions Live preview (26 days out) Key Takeaways Three principles separate professional listings from amateur ones — font pairing (serif + sans-serif), grid and layout (hierarchy: 1, 2, 3), and colour (complementary base + one contrasting action colour). Google Stitch is the best free tool right now for design mockups — unlike image generators (Gemini, GPT), Stitch understands design principles and generates layout-aware mockups you can iterate on. Pretty does not convert on its own — the live test showed the original, information-heavy image outperforming the cleaner redesigns early. Design is a layer on top of strong product information, not a replacement for it. Perplexity can run Stitch autonomously — paste a product title, bullet points, and a reference image; let it loop through Stitch without touching anything; come back to a full brand kit. You can test design variations with 50 real shoppers in under 10 minutes — Product Pinion lets you run image split tests with category-targeted shoppers, get qualitative feedback, and iterate the same day. Nano Banana outputs in Stitch cannot be regenerated — switch to one of the standard models if you need variation or refinement controls. AI gets you to the concept stage fast — use Stitch to generate the direction, then hand to a designer for finishing. Revision cycles and meetings shrink dramatically. Notable Quotes "If everything is important, nothing really is." — Dorian "The hardest thing is to make something simple, elegant, and something that people get instantly." — Dorian "Pretty is one thing, but the information has to be there. I didn't put the information there — and it's not doing well." — Dorian (on live split test results) "Most people don't necessarily know good design, but they know what they like. It's more of a feel — they go, that looks a bit cheap, or that looks really good." — Danny McMillan "It's never been easier and faster to become a world-class brand on design. Plug in your details, get a design guide going, and you can really up your brand in a very short period of time." — Matt Kostan "The breakout brands from the Amazon community — we haven't had enough of them crossing over. Now that gap's closed." — Danny McMillan Resources Mentioned Google Stitch — Free AI design tool; generates brand guidelines, font pairings, mockups, A+ content concepts, and layout variations. Up to 3,000 generations per day (free) Figma — Design tool used by Dorian to pull Stitch outputs and refine layouts manually Adobe Color (color.adobe.com) — Colour palette exploration and complementary colour tool; used in the live demo for the wood/blue beach-forest palette Coolers.co — Free colour palette generator with AI colour bot and real-world visualiser Pinterest — Recommended for browsing font pairing inspiration Nano Banana 2 — Image generation model available inside Stitch; note: regeneration/variation controls don't work on Nano Banana outputs Perplexity — Used to autonomously control Google Stitch via browser automation, building a full brand kit end-to-end from a single prompt Product Pinion — Consumer research and split testing tool by Matt Kostan; image tests with real shoppers, category targeting, results in minutes. Product Pinion API + Claude integration in development. Guest Info Dorian — Design and conversion specialist, Seller Sessions Conversion Monthly co-host Matt Kostan — Founder of Product Pinion, consumer research and split testing for Amazon sellers