TileMill is a powerful open source map authoring tool, developed by Mapbox. With TileMill, you can transform both vector and raster geodata into beautiful, interactive map packages, which can be loaded into your Fulcrum app and used entirely offline. While TileMill is an extremely powerful application, it can be somewhat intimidating for first time or casual users. This guide is designed to help you become more familiar and comfortable using TileMill for creating interactive, offline maps and map packages for use in Fulcrum. For additional information, please refer to the TileMill documentation or visit the Mapbox support forums. TileMill is available for Ubuntu, Windows, and Mac OS X. Consult the documentation for your particular platform and proceed once you have successfully installed the application. If you run into any issues during the install process, refer to the Troubleshooting guide. TileMill is powered by the Mapnik toolkit and utilizes CartoCSS styling. If you are familiar with CSS, CartoCSS should look recognizable, though the properties are different. CartoCSS is fairly straightforward, but be sure to reference the documentation for the particulars. If you are simply trying to create an offline basemap to view in Fulcrum, feel free to skip this step. If you are working with raster data, such as an aerial image, there are no attributes to display and you can simply export out the image tiles in the next step. However, if you are working with vector data, it is often advantageous to be able to view the attributes associated with each feature. TileMill takes advantage of UTFGrid technology to efficiently encode attribute data for use in MBTiles map packages. Fulcrum currently supports the Teaser and Full template objects. The Teaser can be thought of like a Title, while the Full object contains additional information. After selecting the layer you want to be interactive, you are presented with a list of mustache tags, representing the data attributes of the layer. These tags will be replaced by the actual data in the map package. For security purposes, Templates have limited support of HTML. Styles <,strong>, and line breaks <,br>, are supported, but hyperlink tags <,a>, appear to be sanitized and removed from the MBTiles file. Note- these tags can be manually added outside of TileMill by editing the “metadata” table in the resulting .mbtiles SQLite file. To preview the feature interaction, make sure to click the Save button after defining your templates. Hover over a feature to view the Teaser and click on a feature to view the Full information. Now that you have created a custom offline MBTiles map package, you can load this file directly onto your mobile device, heres how to do that for your device: Source.