An X-ray mask structure includes a unibody support substrate having at least one thinned portion surrounded by a wall portion, a top layer disposed on the at least one thinned portion of the support substrate, and a plurality of X-ray absorber patterns disposed on the top layer over the at least one thinned portion. In one embodiment, a voltage regulation circuit includes a current sense circuit having a current sense terminal to conduct a current to be sensed by the current sense circuit. When air and seed are send through the delivery line, a control cover may be moveably positionable over the porous medium to control the flow of air through the porous medium and to start, stop, or otherwise control the dense phase transport of seed through the dense phase delivery line. The pre-forming tool is lowered to a first stage closed position thereby trapping edges of the sheet between binder surfaces of the tools. A disposable shackle system allows the customer to replace the cut shackle and return the lock to its original condition for reuse.