Die-cast robust metal body in corporating new, compact design. The low friction wheels have individual spring suspension making them retract into the body to protect the trolley from damage due to fall or accidental skateboarding. Two metal locking pins provided at the top of trolley facilitates secure stacking of two or more trolleys to increase the effective mass 2-3 times its basic mass. The front end of the trolley incorporates a spring loaded exploder plunger with release trigger knob at the top, with the rear end having a clamping screw for attaching tape of ticker timer.