Go to the following file

Documents>Teardown>Savegame

open savegame in a program such as notepad

paste the following in and save:
<registry version="0.5.2">
<savegame>
<tool>
<sledge>
<enabled value="1"/>
</sledge>
<spraycan>
<enabled value="1"/>
</spraycan>
<extinguisher>
<enabled value="1"/>
</extinguisher>
<shotgun>
<enabled value="1"/>
<ammo value="96"/>
<range value="60"/>
<damage value="5"/>
</shotgun>
<rocket>
<enabled value="1"/>
<ammo value="24"/>
<damage value="5"/>
</rocket>
<pipebomb>
<enabled value="1"/>
<ammo value="36"/>
<damage value="4"/>
</pipebomb>
<gun>
<enabled value="1"/>
<ammo value="36"/>
<range value="100"/>
<damage value="3"/>
</gun>
<bomb>
<enabled value="1"/>
<ammo value="36"/>
<damage value="6"/>
</bomb>
<blowtorch>
<enabled value="1"/>
<ammo value="60"/>
</blowtorch>
<plank>
<enabled value="1"/>
<ammo value="64"/>
<width value="5"/>
<length value="64"/>
</plank>
</tool>
<message>
<boss_intro value="2"/>
<mall_intro value="2"/>
<boss_busted value="2"/>
<lee_computers value="2"/>
<lee_login value="2"/>
<boss_coffee value="2"/>
<lee_safe value="2"/>
<caveisland_computers value="2"/>
<mansion_race value="2"/>
<caveisland_dishes value="2"/>
<marina_demolish value="2"/>
<dev_thanks value="2"/>
<lee_safe_done value="2"/>
<marina_cars_reminder value="2"/>
<boss_encourage_1 value="2"/>
<mansion_art value="2"/>
<lee_powerplant_done value="2"/>
<frustrum_chase value="2"/>
<marina_tools value="2"/>
<boss_encourage_2 value="1"/>
</message>
<mission>
<mall_intro value="1">
<score value="1"/>
<timeleft value="-1.0"/>
<missiontime value="1.1"/>
</mall_intro>
<lee_computers value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="4.8"/>
</lee_computers>
<lee_login value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="2.3"/>
</lee_login>
<lee_tower value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="4.8"/>
</lee_tower>
<lee_safe value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="4.8"/>
</lee_safe>
<lee_powerplant value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="4.8"/>
</lee_powerplant>
<lee_flooding value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="4.8"/>
</lee_flooding>
<marina_gps value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="2.3"/>
</marina_gps>
<mansion_fraud value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="2.3"/>
</mansion_fraud>
<caveisland_dishes value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="2.3"/>
</caveisland_dishes>

<caveisland_propane value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="2.3"/>
</caveisland_propane>
<frustrum_chase value="1">
<score value="3"/>
<timeleft value="-1.0"/>
<missiontime value="2.3"/>
</frustrum_chase>
<mansion_race value="1"/>
<caveisland_computers value="1"/>
<lee_safe value="1"/>
<marina_demolish value="1"/>
<mansion_art value="1"/>
<marina_tools value="1"/>
</mission>
<lastcompleted value="lee_computers"/>
<hub>
<score value="34"/>
<hub2 value="1"/>
<hub14 value="1"/>
<hub16 value="1"/>
</hub>
<valuable>
<lee_whisky value="1"/>
<lee_screwdriver value="1"/>
<lee_tilecutter value="1"/>
<lee_cash3 value="1"/>
<lee_painting4 value="1"/>
<hub_banana value="1"/>
<marina_cashbox value="1"/>
<marina_lubrication value="1"/>
</valuable>
<cash value="999984670"/>
<sandbox>
<enabled value="1"/>
</sandbox>
<challenge>
<ch_lee_mayhem>
<score value="613323908.0"/>
<stars value="5"/>
<scoredetails value="613323908 voxels"/>
</ch_lee_mayhem>
<ch_caveisland_mayhem>
<score value="613323908.0"/>
<stars value="5"/>
<scoredetails value="613323908 voxels"/>
</ch_caveisland_mayhem>
<ch_marina_mayhem>
<score value="613323908.0"/>
<stars value="5"/>
<scoredetails value="613323908 voxels"/>
</ch_marina_mayhem>
<ch_mansion_mayhem>
<score value="613323908.0"/>
<stars value="5"/>
<scoredetails value="613323908 voxels"/>
</ch_mansion_mayhem>
<ch_frustrum_mayhem>
<score value="613323908.0"/>
<stars value="5"/>
<scoredetails value="613323908 voxels"/>
</ch_frustrum_mayhem>
</challenge>
</savegame>
</registry>

you will now have access to all sandbox levels and all tools, as well as infinite cash coz why not