Pay per file, no account

x402 payments for AI agents

Xem Studio sells CAD files to AI agents over x402, the HTTP payment standard: the agent requests a file, the server answers 402 Payment Required with a price in USDC on Base, the agent pays and retries, and the file comes back. No account, no API key, no checkout page. Live on Base mainnet since October 2026.

Same files, two ways to pay: people pay by card on the object page; AI agents pay with x402, no account, 20% less. The library itself stays free for everyone: every dimension sheet, 1397 objects with free STEP/STL, and every page through the browser. Only Xem Studio's sold packs cost money. Pricing · License

What is for sale

Item	Agent price	Endpoint
Snap tri-clamp, bolt-free: STEP + STL, every flange size, a Xem Studio design	$2.40 ($3 by card)	GET /api/buy/snap-tri-clamp-pack
Hydroponic tower kit, printable tri-clamp: every part, assembly guide (coming)	$12 ($15 by card)	GET /api/buy/hydroponic-tower-kit

More items are added to this table as they go on sale. Agents pay 20% less than the card price: x402 has no card fees, and we want agents connected. Everything else on the site stays free. Check what is live: GET /api/buy/_status.

How a purchase works

Ask for the file. GET https://xemstudio.com/api/buy/snap-tri-clamp-pack
Read the price. The answer is 402 with a PAYMENT-REQUIRED header (base64 JSON, x402 version 2): scheme exact, network eip155:8453 (Base), asset USDC 0x8335…2913, the amount in USDC base units, and the address to pay.
Pay and retry. Sign a USDC transfer authorization for that amount and send the same request again with it in the PAYMENT-SIGNATURE header. Any x402 client library does this in one call.
Get the file. The server verifies and settles the payment through Coinbase's facilitator and returns the zip with a PAYMENT-RESPONSE header carrying the transaction.

Protocol: x402.org · specification. Xem Studio implements the HTTP transport, v2, exact scheme on Base. The test network (Base Sepolia) is not offered; purchases are real.

Through the MCP server

Agents connected to the Xem Studio MCP server get the same prices: get_free_files returns free files where they exist and the x402 endpoint where a file is sold. The dimension sheet, fits and sources of every object are always free through get_geometry.

What you are buying

Xem Studio's own designs, under the Xem Studio Design License: use the file for anything, including commercially; print it, machine it, sell what you make. Don't republish the file itself as a download. Files are drawn at true size with no printing tolerance.

Questions or a file you want sold this way: send a request.