I have created a trade machine for players to use at /warp mttrade
It ensures that neither player can leave with the others items, and allows players to cancel the trade if they wish. Its easy, Trader A goes in the front, and Trader B goes around back. Each player turns around, closes the iron door behind them to prevent anyone from interfering, then goes up the stairs and places their desired item they wish to trade on a piston, the items are visable through glass for each player, should the player wish to cancel the trade they may hit the button on the red wool block, which has a piston force their items into a waterway that carries it back to them. To accept the trade, both players must switch their lever on each side towards the up position, allowing each player to collect their items which they traded for, after which they switch the levers back down to reset the mechanism, please try it out and let me know what you think!
It ensures that neither player can leave with the others items, and allows players to cancel the trade if they wish. Its easy, Trader A goes in the front, and Trader B goes around back. Each player turns around, closes the iron door behind them to prevent anyone from interfering, then goes up the stairs and places their desired item they wish to trade on a piston, the items are visable through glass for each player, should the player wish to cancel the trade they may hit the button on the red wool block, which has a piston force their items into a waterway that carries it back to them. To accept the trade, both players must switch their lever on each side towards the up position, allowing each player to collect their items which they traded for, after which they switch the levers back down to reset the mechanism, please try it out and let me know what you think!