An alternative proposition
if you've got access to warforged then:
Wizard 12/Ranger 6/Rogue 2
Could be a fun build.
Alternatively you could go:
Wizard 11/Ranger 9 and dump the whole "traps" idea.
Here are the 28 point build stats and the feats I'd choose for each:
Wizard 12/Ranger 6/Rogue 2
STR 16 - level ups go here
DEX 14
CON 16
INT 14
WIS 6
CHA 6
Wizard bonus feats - Extend, Maximise, Quicken
Regular feats
1 Toughness
3 Power Attack
6 Empower
9 Mental toughness
12 Toughness again
15 Imp crit: Slashing
18: Imp crit: Ranged
Use the ranger levels to max search, that way the rogue and wizard levels can max disable and UMD.
Level progression:
1 Rogue
2-3 Ranger
4-10 Wizard
11-12 Ranger
13- 16 Wizard
17 - Rogue
18 - 20 Ranger
Wizard 11/Ranger 9
STR: 16 - level ups here
DEX: 16
CON: 16
INT: 10
WIS: 6
CHA: 6
Wizard bonus feats - Extend, Maximise, Quicken
Regular feats
1 Toughness
3 Power Attack
6 Empower
9 Mental toughness
12 Imp crit: Slashing
15 Imp crit: Ranged
18: Greater Two Weapon fighting (will need to have eaten a +1 dex tome by this stage but anyone at level 18 should have the means to do that
Level progression:
1 Ranger
2-7 Wizard
8-12 ranger
13 - 17 Wizard
18 - 20 Ranger
Both of these are decent, and different, solo builds. The former is a bit more versatile and survivable (evasion comes earlier, extra toughness feat) the other fights better (GTWF, higher BAB)
Both have:
Spells:
Blur
haste
displacement
firewall
reconstruct
max elemental resists
Fire/Cold shield
Stoneskin
Abilities
Manyshot
Imp 2 weapon fighting
Evasion
Favoured enemies
WF immunities
So both are survivable, self healing, self buffing and with decent melee ability. Get a divine power clicky and never look back.