Something we have been asked to create for many years, a lightweight gambeson/padded tunic.
Gambesons by their nature tend to be thick very padded, uncomfortable to wear, difficult to move in and damned hot and rightly so, the market for these is mainly re-enactment with steel armour metal weapons etc.
So after much thought and discussion with LARPers we've created a lightweight version, it's padded yet comfortable lightweight yet offers enough padding for your armour atop it, and it won't roast you!
Laced at the chest and wrists to allow for small adjustments. It has a high collar to prevent rubbing from armour it runs down to just above the knee to again provide padding around the hips and thighs if required but we have also incorporated splits at the front and back to allow for a wide range of movement, we've also made it machine washable.