During the DSi development panel, DSi design director Masato Kuwahara showed some early handheld prototypes that never made it to market. Like this Game Boy Advance predecessor from 1995, the first prototype for a next-gen color handheld system, shown next to a DSi:
"There's no way you're fitting that thing in your pocket," Kuwahara said via a translator. "You would be shocked to see how big that device was." He also said that the graphics engine wasn't proficient, and that there were performance issues.
The next prototype shown was a touch-screen adapter that Kuwahara designed to attach to the Game Boy Color. He said it was not "favorably received" by the software development team because the LCD screen didn't have a backlight. He also revealed that Miyamoto liked the adapter when it was used on the GBA SP, but it was not brought to market. Kuwhara was disappointed but said, "I'd like to to think my prototype led to the appearance of the Nintendo DS."