Abstract: A pen track has an outer shell, a transmitting group, a rotating group, and a linking group. The transmitting group is mounted in the outer shell and has a portion rotatably abutting a drawing surface. The rotating group is mounted in the outer shell and has a modeling block. The modeling block is mounted in the outer shell, is rotated with the transmitting group, and has an outer surface and a modeling segment annularly formed on the outer surface of the modeling block and having multiple curved surfaces connecting each other. The linking group is mounted in the outer shell and has a pushing protrusion pressed against the modeling segment of the modeling block to move the linking group reciprocally relative to the outer shell along the curved surfaces of the modeling segment.

Abstract: A ratio tape measure has a case, a reeling unit, a ratio wheel unit, a decurling wheel, and a tape measure unit. The case has a reeling shaft, a ratio shaft, and a decurling shaft. The ratio wheel unit has a first perimeter wheel mounted around the ratio shaft and a second perimeter wheel mounted around the ratio shaft. The decurling wheel is rotatably mounted around the decurling shaft. The tape measure unit is wound around the reeling unit and the ratio wheel unit and has a first tape and a second tape. When the first perimeter wheel and the second perimeter wheel rotate, the first tape and the second tape can be pulled out at a fixed ratio, and a user can measure two lengths at one time.

Abstract: A pen track has an outer shell, a transmitting group, a rotating group, and a linking group. The transmitting group is mounted in the outer shell and has a portion rotatably abutting a drawing surface. The rotating group is mounted in the outer shell and has a modeling block. The modeling block is mounted in the outer shell, is rotated with the transmitting group, and has an outer surface and a modeling segment annularly formed on the outer surface of the modeling block and having multiple curved surfaces connecting each other. The linking group is mounted in the outer shell and has a pushing protrusion pressed against the modeling segment of the modeling block to move the linking group reciprocally relative to the outer shell along the curved surfaces of the modeling segment.

Abstract: A ratio tape measure has a case, a reeling unit, a ratio wheel unit, a decurling wheel, and a tape measure unit. The case has a reeling shaft, a ratio shaft, and a decurling shaft. The ratio wheel unit has a first perimeter wheel mounted around the ratio shaft and a second perimeter wheel mounted around the ratio shaft. The decurling wheel is rotatably mounted around the decurling shaft. The tape measure unit is wound around the reeling unit and the ratio wheel unit and has a first tape and a second tape. When the first perimeter wheel and the second perimeter wheel rotate, the first tape and the second tape can be pulled out at a fixed ratio, and a user can measure two lengths at one time.