I have been starting to flesh out a campaign using the Tangents rules (Project Slipstream:
http://www.wirepaladin.co.uk/viewtopic.php?t=27) .
The really good thing about the old Tangents book is that the world generation rules don't need to be converted, leaving very little to convert.
Quantum Tunneler
A Quantum Tunneler resembles a large PDA. The screen gives the user feedback as to the current state of the system. When activated it creates a 10ft diameter tear between dimensions that lasts for a short time. Unless the user is attempting to lock onto a previously activated Quantum Transponder the tear opens out onto a random dimension.
Activating a Quantum Tunneler requires a Knowledge(Physical sciences) or Knowledge(Technology) roll (DC 25), you can not take a 10 or a 20 on the roll.
Natural 1; No tunnel. Looses quantum synchronization, 1d10 + 10 days to re-synchronize.
2-24; No tunnel. Looses quantum synchronization, 4d20 hours to re-synchronize.
25-39; Tunnel created, lasts 1d6+4 rounds, 1d10 hours to re-synchronize.
40-49; Tunnel created, lasts 2d8+6 rounds, 1d10 minutes to re-synchronize.
50+; Tunnel created, lasts 2d10+6 rounds, no synchronization required.
There is a 20% of becoming permanently lost if you attempt to activate the tunneler before it has resynchronized .
Quantum Transponder
A Quantum Transponder resembles a high tech coat stand that folds down into a small briefcase. When activated it provides a beacon for dimension travelers to lock onto.
Oviously none of this technology is available for sale, hence no purchase DC.