  We propose and experimentally demonstrate the Transformable Reflective
Telescope (TRT) Kit for educational purposes and for performing various optical
tests with a single kit. The TRT Kit is a portable optical bench setup suitable
for interferometry, spectroscopy, measuring stray light, and developing
adaptive optics, among other uses. Supplementary modules may be integrated
easily thanks to the modular design of the TRT Kit. The Kit consists of five
units; a primary mirror module, a secondary mirror module, a mounting base
module, a baffle module, and an alignment module. Precise alignment and
focusing are achieved using a precision optical rail on the alignment module.
The TRT Kit transforms into three telescope configurations: Newtonian,
Cassegrain, and Gregorian. Students change telescope configurations by
exchanging the secondary mirror. The portable design and the aluminum primary
mirror of the TRT Kit enable students to perform experiments in various
environments. The minimized baffle design utilizes commercial telescope tubes,
allowing users to look directly into the optical system while suppressing stray
light down to $\sim$10$^{-8}$ point source transmittance (PST). The TRT Kit was
tested using a point source and field images. Point source measurement of the
Newtonian telescope configuration resulted in an 80\% encircled energy diameter
(EED) of 23.8 $\mu$m.
