Imaging epitaxially grown magnetic materials, e.g. magnetic oxides at high spatial resolution is of great interest both fundamentally as well as technologically. Currently, however, studies have been limited mainly to samples that can be fabricated on amorphous silicon nitride membranes. We have designed and built a jet-etcher, which is used to backside-thin epitaxially grown magnetic samples and have also developed several specific sample fabrication and etching procedures. The prepared samples have been measured using the high-resolution magnetic soft x-ray microscopy beamline 6.1.2 at the Advanced Light Source in Berkeley, CA. We are the first to obtain XMCD contrast for LSMO samples in transmission. We also report on the first single crystalline MgO membranes. With this work we built up the foundation for future studies on nanostructured LSMO samples as well as for other interesting materials. It can be foreseen that the study of single crystalline materials at very low spatial resolution will contribute significantly in order to develop next generation spin based devices.