It is also possible to have the D2 modified for button-tops! https://budgetlightforum.com/t/interest-collect-k9-3-new-configuration-option-uv-channel-and-the-same-option-for-the-dm1-12-in-the-future/57210/6226

Hank Wang: You can always request us to modify the driver a bit (remove the spring), so that D2 can work with the unprotected, button top 14500 battery only