Tissue patches and associated systems and methods are described. Certain embodiments are related to inventive systems and methods in which tissue patches can be made quickly and robustly without the use of complicated fabrication or sterilization equipment. For example, in some embodiments, tissue patches are made by applying a compressive force to a liquid medium comprising fibrinogen (and/or fibrin) between two surfaces (e.g., within a syringe or other chamber). A filter can be placed within or near the volume in which the compressive force is applied to the liquid medium such that unwanted material (e.g., water, blood cells, and the like) is passed through the filter while desirable components (e.g., fibrin, fibrinogen, and/or other desirable components) are retained by the filter to form the patch. In this way, the concentration of fibrin (and/or fibrinogen) within the liquid medium can be increased, potentially dramatically, as the compressive force is applied to the liquid-containing composition. In addition, in some embodiments, at least a portion of the fibrinogen and/or fibrin can chemically react (e.g., the fibrinogen can polymerize to form fibrin and/or the fibrin can cross-link) during application of the compressive force. Reaction and concentration can lead to the formation of a highly-concentrated, mechanically robust patch that can be handled relatively easily and provide good structural reinforcement at a wet site, such as a bleeding wound.