A low cost digital ruler with desirable ergonomic characteristics and accuracy. A low friction sliding position indicator includes a compliant element that forces its connection pads against the ruler's electronic scale contacts, to determining measurement positions. The position indicator includes an instrument receiving feature that engages a writing instrument and moves in conjunction with it, thereby measuring a line as it is drawn. A position indicator preload arrangement includes the compliant element, which is deflected to exert a preload that forces the sliding position indicator against a housing of the digital ruler. Alignment features of the position indicator and housing have cross sections that provide a self-aligning angled interference fit, which accurately aligns the sliding position indicator, under the action of the preload force. Misalignment constraint surfaces constrain the sliding position indicator in approximate alignment by, even if an external force overcomes the preload force.