Lamp demos
18 gauge lamp cord (zip cord) with ribs or markings for the neutral
https://www.amazon.com/Conductor-Electrical-Flexible-Extension-Stranded/dp/B0DFVGNBDF
socket (no switch)
https://www.amazon.com/Socket-Standard-Screw-Pendant-Bulbs-18/dp/B082LT9HWB
plug
https://www.amazon.com/Leviton-101-P-Residential-Polarized-Non-Grounding/dp/B000U3HYTW
12 volt DC bulb, E26 Edison base, low wattage (1 watt or so for longer battery life)
https://www.amazon.com/Tupolife-Voltage-Equivalent-Christmas-Halloween/dp/B0CFG4LDRB
or
https://www.amazon.com/LDCHIUEN-Edison-Medium-White-Voltage/dp/B08LZHWWTW
DC outlet boxes
Duplex receptacle
https://www.amazon.com/Leviton-T5320-IMP-Resistant-Receptacle-10-Pack
or
https://www.homedepot.com/p/Leviton-15-Amp-125-V-Duplex-Outlet-Receptacle-Ivory-1-Pack-5320-I-R51-05320-00I/100044028
1-gang "new work" box (pull out the nails)
https://www.homedepot.com/p/Carlon-1-Gang-18-cu-in-Blue-PVC-New-Work-Electrical-Switch-and-Outlet-Box-B118A/202546986
Duplex outlet plate (match the style of the receptacle - designer (rectangle) vs old school, rounded corners)
https://www.homedepot.com/p/Carlon-1-Gang-Gray-Non-Metallic-Handy-Box-Duplex-Receptacle-Cover-HB1DP/202077376
9 volt battery (rechargeable if you have the budget - better in the long term)
https://www.amazon.com/dp/B0CKN55D1Y
9 volt battery clip
https://www.amazon.com/Battery-Connector-Plastic-Experiment-Equipment/dp/B08SL9X2YC
Optional:
Panel-mounted switch, round, 12 volt indicator light if desired
https://www.amazon.com/Mandark-Waterproof-Round-Rocker-Switch/dp/B0D8T3D154/
Barrel jack, panel mounted, round, 5.5mm x 2.1mm
https://www.amazon.com/Antrader-24pcs-Female-Socket-Connector/dp/B07CTCLKPP
9 volt battery clip with barrel plug
https://www.amazon.com/dp/B09MZ8Y4LL
Tools:
Multimeter
Stubby philips head screwdriver
Wire strippers