A Travel Pad is a small dance pad typically around 20" x 20" (51cm x 51cm). As the name implies, this dance pad is much easier to travel with. Due to the fact that the panels are typically about 1/3 to 1/2 the size of a full pad, it is mostly used for stamina play.
Internet user 4199 is typically credited with the concept and basic form factor of the travel pad, although the first proof of concept -version of travel pad with a building instructions was released already in 2018 by Renbrandt.
4199's video can be found here: https://www.youtube.com/watch?v=h3qDn847Iio
dj505 has a build log for their travel pad here: https://imgur.com/a/IuHijaS
Teejusb has a set of plans and instructions using the above two for inspiration here: https://github.com/teejusb/teejusb-pad