PeaZip, another compression tool which can compress to many different formats and also does batch compression to individual files. This is the portable version, so no need to install it, just extract it somewhere.
Add the files to your 7z folder in either Program files or Program Files (x86).
Run "7zip Batch Compression.exe"
Drag & drop your files.
Choose the archive type and compression.
Hit "Start Compress".
Original link.