  We present a laboratory electromagnet capable of generating magnetic fields
up to $\pm$0.48T, specifically designed as a perpendicular flux source for thin
film samples in an ambient environment. The magnet features a 250mm diameter
clear access bore above the sample plane, thus offering compatibility with a
wide variety of experimental apparatus. Despite its generous size, the magnet
thermally dissipates less than 1kW at maximum field. A shaped ferromagnetic
core is used to amplify and homogenize the field $\mathbf{B}$, leading to an
estimated uniformity of $\pm$1.5mT ($\lesssim$0.3%) in
$\left|\mathbf{B}\right|$ within a 28mm$^2$ zone at maximum field. The sample
stage is thermally regulated and isolated from the magnet, enabling temperature
control with $\pm$5mK precision even at elevated magnetic fields.
