Manufacturer-made light guide (MMLG) tips of light emitting diodes (LEDs) are frequently damaged. Could custom-made light guide (CMLG) tips be suitable replacements? 1.) To compare compressive fracture strengths of resinbased composite specimens photo-polymerized/ cured with a CMLG tip (acrylic-glass) and a MMLG tip (fibre-optic), used interchangeably on a poly-LED curing unit. 2.) To compare the costs of the CMLG tip and the MMLG tip. Two groups of 20 composite cylindrical specimens (4 mm diameter, 4 mm length) were made in teflon moulds. Each light tip cured ten micro-hybrid Z100 TM and ten nano-filled Filtek TM Supreme XTE specimens, (60 seconds each side). Storage was in distilled water at 37°C (±2°C) for 48 hours. Compressive strength testing (MPa) was done at a crosshead speed of 0.5 mm/min using a Bencor Multi-T device in an Instron machine. Student's paired t-test and intra-class correlation coefficients (ICC) were applied for analysis and agreement testing. Relative costs of both light guide tips were determined and compared. Only the Z100 TM groups showed significant differences in compressive fracture strength (p = 0.001). The CMLG tip was cheaper.