Roblox: see it on an avatar (free)
Put your exported shirt on a test body in Roblox Studio. No fees, no uploads to the store, just your design on an avatar.
Video coming soon — the written walkthrough below is the whole build.
Written walkthrough
This is the payoff walkthrough: your design on a body, for free. You need a computer with Roblox Studio (free download) and a Roblox account (also free). No Robux involved anywhere in this one.
1. Export the Roblox PNG
In Ünflat: ↗ Share & Export, tap Roblox, then Download .png. Get the file somewhere your computer can reach it (the share sheet, a drive, an email to yourself, whatever’s easy).
2. Open Studio and spawn a block rig
New place in Studio, then the Avatar tab: Character, and pick a Block Avatar rig. A gray test body drops into the world. Classic clothing was born on blocky avatars, so this rig shows your shirt exactly as designed.
3. Import your picture
Drag your PNG into Studio’s Asset Manager (View tab if it’s hidden). Studio uploads it to your account as an image, free. When it appears, right-click it and Copy asset ID.
4. Dress the rig
In the Explorer, hover the rig, press the ➕, and insert a Shirt (or Pants, or ShirtGraphic for a t-shirt). Select it and paste your asset ID into its ShirtTemplate property (PantsTemplate for pants, Graphic for t-shirts). Studio sorts out the ID format on paste, and the shirt wraps onto the body.
Spin the camera around your dressed avatar. That’s your clothing, on a body, and it cost nothing. Selling it on the Marketplace is a separate walkthrough with real fees, so only head there when you’re ready.