This grouting gun could be useful for both big and small projects. There's no cord to restrict you, just make sure you've charged the battery.
From Data Powertools
DeWALT DCE581N-XJ 300-600ml 18V XR Cordless Caulking Gun Body Only
ITS
Dewalt DCE581N 18V XR Cordless Caulking Gun with Cartridge Holder (300-600ml) - Body