For previewing purposes, a lot of 3D models / CAD files can be exported and saved as simple pictures. So it should be possible to export models in STP format and create a BMP picture from them. Some viable software capable of this are listed below.
Convert ISO-10303 STEP product data to Standard Windows bitmap image.
We have found 2 software records in our database eligible for .stp to .bmp file format conversion.
Microsoft Windows software - convert stp to bmp on Windows
A 3D modelling application
Convert from stp file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned stp to bmp. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A 3D product data optimalization software