For all the thermal scope users, I recently came across a company that offer thermal targets. GlowShot is an Australian company based in Melbourne and sell a range of shooting targets, including targets specifically designed for thermal optics.
The passive thermal targets seen above allow you to sight in and practice with your thermal optic. The targets are made from a unique material that has a natural thermal contrast and does not require any power source. The zeroing targets are adhesive and provide 1cm grid for easy correction of point of impact. The targets are made to work in any weather conditions.
As well as the range of military targets available, GlowShot also offer a variety of reactive splatter targets. These targets work when the bullet passes through the target, it removes the top layer, exposing the coloured layer underneath, creating a coloured halo effect around the impact.
You can find more information on GlowShot targets on their website.