| Business | Phone |
| Architectural Consulting Engrs 837 Hayes Ave, Oak Park 60302 | (708) 524-0272 |
| Associated Business Conslnts 1011 Lake St 312, Oak Park 60301 | (708) 848-7817 |
| Brewer Engineering Co 229 N Ridgeland Ave, Oak Park 60302 | (708) 386-3641 |
| Fluidclarity 126 N Oak Park Ave, Oak Park 60301 | (708) 383-3500 |
| Continental Engineering Corp 1122 Edmer Ave, Oak Park 60302 | (708) 848-8200 |