The William Optics RedCat is rapidly becoming a highly sought after lens. Part of its appeal is its versatility, with the option to add a diagonal and eyepiece and hence transform it into a compact telescope. If used in its principal role as a camera lens, one could attach a small guiding telescope/camera. Or when used visually, a finderscope might be desirable to affix.
For either role, William Optics offers a mounting base for the attachment of accessories having a Vixen style mount. This permits a self-contained system that is also rigid and compact. The base weighs a mere 5g, and attaches directly to the RedCat.
Among finders, you can select one of the optical type, such as a 6X30 or 8X50. Until now, the smaller guidescopes have been of 50mm aperture. But perhaps the ultimate in a matching, compact guide scope would be the QHYCCD miniGuideScope, having a 30mm aperture f/4.3 objective--perfect!