1 Most engineering artifacts are designed and analyzed2 today within a 3-D computer aided design (CAD)3 environment. However, slender objects such as beams are4 designed in a 3-D environment, but analyzed using a 1-D5 beam element, since their 3-D analysis exhibits locking6 and/or is computationally inefficient. This process is7 tedious and error-prone.8 Here, we propose a dual-representation strategy for9 designing and analyzing 3-D beams, directly from within a10 3-D CAD environment. The proposed method exploits11 classic 1-D beam physics, but is implemented within a 3-D12 CAD environment by appealing to the divergence theorem.13 Consequently, the proposed method is numerically and14 computationally equivalent to classic 1-D beam analysis15 for uniform cross-section beams. But, more importantly, it16 matches the accuracy of a full-blown 3-D finite element17 analysis for non-uniform beams.18