The LILLABO toy train tracks have plastic connectors that are designed to be compatible with BRIO tracks. However, the fit is very tight and thus LILLABO tracks might not be compatible with all third-party (cheapo) tracks out there. This connector is 2mm longer than the original, thus allowing tracks to be compatible with virtually any wooden train set. As a drawback, connections will be looser. The length can however be easily customized to achieve what you want.The design is fully adjustable and can be customized to fit your needs. Adjust the value of the 'stud_length' variable in the SCAD file to control the length of the connector (the original IKEA piece is 20mm). Or use the Customizer to do that. The four little nods on the larger end of the connector are to secure it firmly in the track. Depending on your fabrication method, you might need to adjust the nods so that the connector can be easily sled into the track yet remain firmly in place. The 'nod_recess' variable indicates how deep the nods are recessed in the surface. The lower the amount, the more the nods will stick out. Try it out! I used 3D printing to make these, but they could also be cut out of wood or MDF with a laser or router. Enjoy!