This spectroscope is magic.
Takig an hour to build, I made one today and took the spectrum of a compact flourescent light, I tried an incandescent bulb first but didn't get lines. The slit is made with two sections of razor blade mounted on Prestick (Blue Tack etc).
The bottom half of the image is as taken, the top has been pushed to show how much detail there really is.
Details of the spectroscope are available at the following address:-
https://pantherfile.uwm.edu/awschwab/www/specweb.htm