A paint bucket, with some modifications, makes up a nice enclosure for the battery and electronics.
A 35Ah battery is held in place with an L-shaped metal part originating from an old old SCSI flatbed scanner power supply. As it is made of perforated metal, it is ideal to mount the electronics on there. The metal part is mounted to the bucket with rivets.
Holes were drilled in the bucket to let moisture out. I don't plan to overcharge the battery but if it does by some reason, the fumes should have a way out, too.
Front-panel-mount-type fuse holders and battery terminals are ordered and should arrive in some days...