The final (?) update for the Little Orange Monster:
1. Even though I don't think it's necessary, I added a tiny 1-inch fan. It was annoyingly loud and whiney, so I rigged it to run from +5V instead of +12V. Now it's much quieter, but also turns more slowly and moves less air. After several hours of run time, the hottest internal temperature is 113 F / 45 C on the bottom of the logic board near the serial ports. The CPU temperature is about 90 F / 32 C.
2. I relocated the speaker, using a very professional scrap of cardboard to float it above the RAM. It's sandwiched tight when the case's top is installed. I thought this might cause muffled sound, but it's not at all.
Here you can see the fan and speaker placements:
3. Added some stick-on feet to the case bottom, so it sits about 4mm above the desk. This provides a little more airflow to the bottom vents. I went overboard with the feet, and used 10 of them!
4. Stole some RAM from the detestable Performa 6205, so now this machine has 36 MB.
5. Now that I know how to transfer software to the SCSI2SD card, I loaded it up with everything I could find. That includes the Tetris Max source code, other strange pieces of shareware that I wrote, Hypercard stacks I made in 1989, SoundMaster audio recordings I thought were hilarious when I was 18, and other gems.