Bing, Bub, Kibri, Marklin, Fandor... are all possibilities. Are there any embossments, stampings or markings? The blue cylinder is indeed a bell- this is a warden's house for a crossing. The base appears to have been replaced- it should be lithographed or painted so it looks like grass/dirt- a hallmark of prewar German structures. The base might be original, could've been someone's project and the base was in such bad shape they removed the flaking paint but never got around to finishing.
If you really want to find it, check this link it's a go-to for me when identifying prewar. I'd Check under the following in this order: Bub, Kibri, Bing, Markling, Carette, Fleischmann, Issmayer, Kraus-Fandor and Distler.
