After watching too much CSI I saw that genomic DNA was surprisingly stable at room temperature and could be isolated from an array of juices using cotton buds etc. It's kind of like making pressed flowers or a herbarium.
As there is already an excellent instuctable for a PCR machine (http://www.instructables.com/id/Coffee-Cup-PCR-Thermocycler-costing-under-350/ ), a method for rapid DNA template isolation may be of use.
SAFETY - Most people or animal juices have the potential for the transmission of pathogens so please take appropriate precautions.
Never lick the spoon when you are doing (non food based) Science!
I have used this method thousands of times with varrious plant materials. For Arabidopsis thaliana and Medicago truncatula the filter paper worked well, for more crunchy leaves from plants such as Ricinus communis I could get a green juice out but not much luck with PCR products, it could be the more robust leaf architecture prevented genomic DNA leaking out as well or it could have been inhibitory factors.
-Non absorbent disposable backing
I used parafilm (like a thick clingfilm) but clingfilm (e.g. saran wrap) could be used.
I used filter paper. Tissue paper is proably too thin but a thin absorbent craft card may work.
I used a plastic container, you need to crush the leaf so anything from a hammer to a plastic cola bottle could be used.
I had access to medical biopsy punches and I could get a good few uses before it got too blunt. A standard ring-binder hole punch will give you disks but they will be big and soak up a lot of PCR mix. Leather punches for belt holes work a treat.
Step 1: PCR basics
Briefly PCR (polymrease chain reaction) is a method by which a small number of copies of a specific sequence can be amplified many thousands of times. This would be useful to generate enough DNA for sequencing or for checking the success of a cloning step.