Sex machines are powered frames that thrust an attached dildo on a set stroke. They overlap with the cruder catalog name “fucking machine,” but the better builds look like exercise equipment: rails, cranks, emergency switches, a stable footprint.

Stroke length, angle, and speed should adjust independently. A machine that only goes harder is a novelty. One that can whisper at a shallow depth is a tool. Attachments need a lock, not a polite friction fit.

Budget time for setup. An unsecured machine walks. An off-angle shaft bruises. Hair and bedding belong nowhere near belts. If you use the machine alone, the off switch must be reachable in the position you will actually be in, not the position in the brochure.

House rules

• Bolt or weight the base.
• Use toys made for mechanical torque.
• Give motors a cooldown.
• Wipe rails so lube does not become a skating rink for the carriage.