  We present the design and experimental demonstration of an open-endcap radio
frequency trap to confine ion crystals in the radial-two dimensional (2D)
structural phase. The central axis of the trap is kept free of obstructions to
allow for site-resolved imaging of ions in the 2D crystal plane, and the
confining potentials are provided by four segmented blade electrodes. We
discuss the design challenges, fabrication techniques, and voltage requirements
for implementing this open-endcap trap. Finally, we validate its operation by
confining up to 29 ions in a 2D triangular lattice, oriented such that both
in-plane principal axes of the 2D crystal lie in the radial direction.
