Eeexcellent. This could be an incredible multi-stage puzzle. Could fill an entire chapter.
The player has to:
1) Get a photograph of the guy's fingerprints.
You have: Glass/CD/whatever with fingerprints. Mug. Digital microscopic camera. Superglue. Heat lamp used for lizard terrarium. Small aluminum/tin measuring cup. Cardboard box. Tape. A table near an electrical outlet.
You need to use the process of cyanoacrylate fuming, or "The Superglue Method," to make the prints clear enough to photograph.
1. USE box on table. PC puts box on table, on its side, so that there's a work space.
2/3/4/5/6/7. USE lamp on box. Player positions lamp so that it is on the table, poking into the box, bulb facing upwards.
2/3/4/5/6/7. USE mug on sink to fill it with water.
2/3/4/5/6/7. USE mug in box. Player puts it in box. This is needed for humidity. (PC will not plug in the apparatus if this isn't done, and will say "I need a humidity source in there. It's too dry to fume well.")
2/3/4/5/6/7. USE cup on lamp. Player puts cup on lamp.
2/3/4/5/6/7. USE tape on CD, then USE CD on box to hang it in the chamber. Just using the CD directly gives the message: "I shouldn't just toss it in haphazardly. I need it to be better exposed."
2/3/4/5/6/7. USE superglue on cup. Note that we'll assume it doesn't dry, or, alternatively, set a time limit that forces to player to add more superglue if this takes too long.
8. HAND icon on box to close it around the lamp neck.
9. USE tape on box to seal it.
10. HAND on plug to plug in lamp. Time passes.
11. HAND on box to open it.
12. USE camera on now-fixed-and-easily-visible prints. Bingo.
I can't help it... that source page looks so much like an adventure game walkthrough...
How does the player figure all this out?
One possibility would be to have the player watch a forensic detective use a fume chamber earlier, and note down the steps in a handy pocket notebook. The fume chamber wouldn't run on over-the-counter superglue, but the principles would be explained. Also, there would be ample tips as to when the player was on the right track. Another possibility is that the player character is a detective, and says things like, "Okay, I need to build a fume chamber myself, then. Need cyanoacrylate, a humidity source, a fume container, and a heat source."
2) Make a mold.
You have: Computer with camera interface. Inkjet printer. Photo-etchable circuit board. UV light.
(Why would the player have photo-etchable circuit board? Well, you can get it from an electronics store, along with a strong UV source, and the electronics shop guy might actually be a good hint source here. "Is there anyway to print a solid object? I mean, to print something out in 3D?" the PC might ask. And the shop guy would tell you what you needed.
1. USE digital camera on computer. Player character uploads picture. Go to Photo Manipulation interface.
2. USE mirror flip option.
3. USE increase contrast option.
4. USE scale option.
5. USE print to Tray 2: Transparencies.
6. GET transparency.
7. USE transparency on circuit board.
8. USE circuit board on UV light.
9. Use tape on circuit board to make a little wall around the print.
3) Make the fake finger:
1. Get the mug.
2. Use gummi bears on mug. The PC will remark that it's got white powder on it from the superglue, and automatically dump it out, put in the bears, and add a bit of water.
3. Use mug on microwave. "It takes you a few tries and a few more gummi bears, but you think you've got it to the right consistency now."
4. Use mug of goo on board.