This stuff is oriented towards 2nd Edition Heavy Gear roleplaying - that's the one I have a pile of sourcebooks for and still use as of now (late 2007). I haven't touched the D20 one, but I have looked at the 3rd ed Silhouette rules and might move to them.
hg_charsheet.PDF - 7,053 Bytes
This character sheet isn't as pretty as the standard one, but has extra spaces for such things as movement speeds, weight, CP, SP and XP.
This is intended to clarify exactly what can be done with different tools; see the HG Rulebook, 2nd edition, page 75 for equipment details. I use the following rules regarding tool sets for Mechanical and/or Electrical tasks.
The 2nd edition rulebook mentions "Jury-rigging" in the descriptions for the Mechanical and Electrical tool kits. For game purposes "Jury-rigging" is defined as a simple merging of two pieces of equipment to form another - such as fixing a sight to a gun, or connecting a speaker to a communicator. Use the higher of tinker and mechanic for mechanical tasks and the higher of tinker and electronic for electrical tasks.
Devices such as WFP Army Knives and Omnitools (i.e. Swiss Army Knives and Leatherman-like devices - see the Equipment Guide) may offer a +1 to Tinker/Mechanical/Electrical rolls at the GMs discretion. This bonus would be less likely to apply for devices with fewer attatchments. This bonus does not apply if there are more advanced tools available - a Mechanical Tool Kit makes your pocket knife redundant.
A Mechanical tool kit can be used for any Mechanical maintenance and repair and is required for advanced modification or building new Mechanical devices. Since mechanical devices use simple physics the GM can allow other devices (including omnitools) and improvised tools to be used at a penalty.
A Electronic tool kit can be used for any Electronic maintenace and repair and is required for advanced modification or building new Electronic devices. Note that electronic equipment such as multimeters and most consumables (with the exception of wire) cannot be improvised so a character without electrical tools will find it difficult, if not impossible, to perform electrical tasks. However, suitable consumables may be acquired by cannibalising other equipment (make a electronics roll to salvage equipment in this way).
Equipment that is both electronic and mechanical in nature, such as most Terranovan vehicles (including gears) require both Electronics and Mechanics rolls to successfully maintain, build or repair. Most cheap civilian equipment (e.g. cars) has very simple electronics, with a routine (2) threshold.
The Tech Rig (2nd edition rulebook page 76) is suitable for most mechanical tasks and some electronic tasks. It is intended to be used by Gear and Vehicle mechanics (see the paragraph above). However it has a smaller supply of consumables and is less suited for construction of new equimpent.