These are inserts made to work alongside T-slotted aluminum extrusions manufactured by FramingTech Inc. Their purpose is to connect two 20mm bars in a way that allows them to slide in a linear fashion. This makes them particularly useful when designing mechanical elements that must travel upwards for a great distance. Items made using 3D Systems printers. There are two types of files included in this set: slides and endcaps. The endcaps are made to be held in place at the ends of each aluminum bar while the slides are allowed to travel freely and act as a form of spacer. Endcaps also come in three different versions, with #1 being the standard and #2 being an elongated version with a protective overhang for pulleys. Endcap #3 does not have a connector piece for a second aluminum bar and is merely meant to prevent parts from sliding out of the aluminum channels. Notice: These parts have been measured to fit smoothly within a FramingTech channel, but not necessarily those of other products. Some filing may be needed to account for differences in printer accuracy. Also keep in mind that these items do wear down over time depending on the material used and may need to be replaced on occasion. To create a lifting device with these parts, start by inserting two endcaps into the channel of the first aluminum bar as shown in image #1. The top endcap will be attached directly to the top of bar one with a self tapping screw. The second endcap will be attached in a similar fashion, except this time to the bottom of another aluminum bar of equal length to the first one (image #2). Continue this process for as long as necessary until the compressed structure looks similar to image #3 and the extended version like image #4. The way this device works is through the use of a pulley system that runs along the outside of the bars. Drill a hole through the top and bottom of each bar (excluding the bottom of the first bar and the top of the second bar) and mount the pulleys as shown in image #5 (sewing bobbins work too). Now take a lightweight cord, feed it through as shown in the image (tying one end to the bottom of the last bar and the other to a winch), and the device is now complete.