Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

Who invented the cement roller?

 The cement roller, also known as a cement roller press or roller press, is a machine that is used to press powdery materials into sheets or other forms. The cement roller was invented in the early 20th century and has since been used in a variety of industrial and manufacturing processes, including the production of cement, paper, and other materials.

It is not clear who specifically invented the cement roller, as the development of this technology likely involved the contributions of multiple individuals and organizations over time. The cement roller is a complex machine that involves a number of mechanical, electrical, and other components, and it is likely that the invention of the cement roller was the result of the combined efforts of engineers, inventors, and other individuals who were involved in the development and refinement of this technology.

Overall, the cement roller is a valuable tool that has played a significant role in a variety of industrial and manufacturing processes. It was invented in the early 20th century and has been continually improved upon and refined over time.